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  The Hollow Machine Y-block Hot Rod is a thing that we had built basically during the time between January 2006 to June 2006 from left over Ford parts. T-hot style street rod that was first used with 272 cid Y-block engine with homemade open headers and an aluminum intake with two DRLA Dellortos on top and without turbos. Almost everything in that machine is homemade. The frame, the body and a lot of different small parts. Later on we drove with twin turbo set up and single turbo set up too.


Hollow Machine has got lots of attention in Magazines this year. Finnish Spinneri -magazine published seven pages of story in two magazines and Y-block Magazine had the whole story published at July-August issue with total of eight pages and lots of pictures.

30th of January 2006. Frame building starts.


Those seats are from Norvegian Fjord boat. Close enough to Ford!


Card board floor mock up under construction.


Card board body under construction. First days of February 2006.


15th of April 2006 things looked like that.


27th of April 2006 body was still like a puzzle.


Same day and we really had some steering issues…


Oh no! That skull again… After all, we couldn’t use that valley cover with our sheet metal intake.


Now here is some attitude! Jyrki playing around and thinking that he is Stirling Moss or something…


Seppo’s kids waiting to see that thing move. Not Jyrki, the machine…


14th of May 2006. Front suspension under construction.


Some tinkering…


24th of May the body was ready to be painted. One thing that we didn’t do ourselves.


And when the body was of the frame, we could do more metal shaping.


Grind and bear it!


Actually, it looked much better than we thought!


28th of May 2006. President of the Ford-Freak Club of Finland at the time, took some laps around the corner as well, while we were building some other stuff.


30th of May. Things are finally looking to get together. Eleven days left and then we should be on the track!


Jyrki installing plug wires.


And Seppo installing steering shafts.


Get wired, you stupid plug or I’ll fire you!


9th of June. Hollow Machine is out of the garage for the first time. And running. See how exhaust manifolds have got some colour…


Flames, flames....


Some stupid mechanic forgot his wrench to the bleeder valve of the left rear wheel cylinder! It stayed there for the whole trailer trip to the first event. Over 200 kilometers. Well, it could have been there forever or until next brake overhaul at least.


Final adjustments before first race at gravel track.


10th of June and right on time! Jim Culver from Texas is leaning on the steering wheel. Oh no, no we’re not going to let him drive!


Yeah, sure hell the fuel pump let us down for the first time and Jyrki had to pull Seppo from the track.


After the pump change, Jyrki went on to the track and showed people some FLAMES!


After the Freak Race 2006 Jyrki painted some stripes on the body.


And of course the skull!


Hmmm… It still needed a windshield and the grill was too high up…


April 2007 and the Hollow Machine was at the FHRA American Car Show.


Driving out of the Helsinki Fair Center. FUN…..!!!


Latest outing was at Finnish Ford Nationals event at Alastaro Circuit July 2009. Seppo waiting at the line up. Grrrrr….




  We drove Our Hollow Machine hot rod with that Dellorto set up for the first weekend at Freak Race 10th of June, 2006, but we couldn’t get it running right. Lots of flames and booms and bangs from here and there. The jetting wasn’t correct and all the other stuff was put together in a hurry too, so, no wonder… For the next outing we changed to a factory original 4V intake and a 600 cfm Holley and drove one Hill Climbing event with that set up. The engine didnt work at all and we were a bit confused and frustrated. What a hell, this should work! We finally found the reason that caused the engine running badly. The spark plugs. Three of the new ones had gone blind probably caused by a too rich air / fuel ratio. After we changed the plugs, it was running ok again and with that setup we raced the last outing of the year at FoMoCo Drag & Track weekend and managed to run a quartermile within 17.5 seconds and with about 125 km/h (80 mph) speed at the end. And we also found out that our steering was horrible without a panhard rod at the front end.

  But, let’s get back to story about turbocharging the Y-block for that vehicle. At first, I’m not an expert in any manner at turbocharging engines. I have read a lot about doing it. Some of that I have understood and some I have passed as "too expensive for me" or "not necessary in our project" reason. Second, this is absolutely not the only and the right way to do it, but this is a story about how we did it and got our beloved Ford Y-block running. I’ll add several pictures to this story to clear out some issues during the build up.

  The block that we are using came to me as a total mystery. I bought it from a friend with 100 euros because it was stuck and it came less one valve cover and less one exhaust manifold. My friend thought that he will never have use for that engine. And I didnt even know what size and what year it was before I started to disassemble parts from it. Way to buy engines, folks!

  Ok. It is a 292 cid C2TE truck block with a forged steel crank and C1TE connecting rods. Not a bad start for the turbo project. And with about 8.2:1 compression figures, it should be okay to put some boost over the pistons. Somehow during the times, water had gone to cylinders number 2 and 8 and seized the pistons completely. It took some time and patience to get the pistons out of the block. Lots of thin oil and hammer whacks made them come out and to my surprise the block needed only honing to clear the cylinder walls. There was no steps on the top ends of the cylinders, so it was ready to get new rings and cleaned up old flat top cast pistons back inside of it. No expensive custom pistons this time!

  And the crank? It was perfect. Just some new Clevite bearings around it and back to block it goes. No balancing either. Why? Itll blow up anyway, so why spend too much money on it! Oil pump was next. Cleaning, inspection and back together. Ok, I did install a suitable shim to the pressure relief valve spring to get the oil pressures to a bit higher level. Of course, that didnt affect anything to the volume of the pump. With turbos it would be good thing to have some more oil volume to lubricate the turbos and everything else too. So that was the oiling issue.

  What camshaft would be good for the task? The truck block had a mild cam inside of it and it was ok from the starting point. However, I took it to the local cam grinder shop which made it to something different. Lift was increased to 7,4 millimeters (0,2913 inch) measured from the lobe. Advertised duration increased to 270 degrees on both sides. Good or bad, who knows? At least its not stock anymore! They made a groove to the center bearing surface too at the same time and the cost for all that was about 100 euros here in Finland. Not bad, if you think about prices for new Y-Block camshafts.

  The timing chain then. I used the old one because it was a roller version and as tight as a new one. So the bottom end was complete and as stock as when it came from the factory. Nothing fancy! Exept the hole in the block skirt at the right side for the returning oil from the right turbo. Yes, the first setup was for two small Garrett turbos and I had to drill a similar hole for the right side as was on the left side where the road draft tube used to be on earlier blocks. I made new block off plates to both sides and mig welded tubes to them pointing upwards to the turbos so that the oil can flow freely back to the oil pan.

  The heads we use? We use the ones that were on the engine when it came to me. C0AE heads and yes, I did a porting job to them. I even got so wild that I went through the walls to the water jackets. Yes, the professional welder took 300 euros of fixing them back to be usefull. I just intended to open up the exhaust runners, but when I was porting the last exhaust port I went a bit too far and made a hole to the wall. Then I checked again the other runners and I found that three more were just about to be gone through. Well, now I know the limit where the walls break... The professional welder then put some more material to all eight exhaust runners to be sure they will hold the water were it belongs.

  I used the original exhaust valves and put a little bit larger SBF (1.71 inch) intake valves to the heads. Valve springs had to be shimmed, because SBF valves are a bit shorter than original Y-block valves. And the locks were at a different height too. Single piece SBF retainers were used to hold the valve springs down. Oh yes, the springs are Ford Motorsport duals without inner springs. A whole lot more seat pressures than with original springs! A three angle valve job was done of course at the build up. So, nothing fancy either here.

  Exhaust manifolds then. Homemades of course. Log style and definetely not the most flowing pieces. We had laser cut flanges and then some pipes to start with and we ended up with working exhaust manifolds that the turbos could be installed. The two small Garrett GT 20 turbos we have, are taken from a container that was going to a scrab yard. Originally they are from a Mercedes Benz Vito series van. Or, should I say, from two of them! They were looking all right and possibly changed by a false diagnosis and as a warranty repair and then thrown to a scrab. Man, they were cheap for me! Those turbos have .45 A/R ratio at the compressor housing and .37 A/R ratio at the turbine housing. Well, we couldnt use those without some modifications because in a real world the internal wastegates were kept closed with a vacuum and then opened by relieving that vacuum. And that action is controlled electrically by the engine control module. Like they do with newer cars. ECM with Y-block? No way! So I got two Mitsubishi Lancer Evolution wastegate pressure clocks from my friend and those open by the boost pressure. The classic way. And that same friend told me that those clocks would open at 0.6 bar (8.7 psi).

  The next step after installing the turbos was the building of the oil feed lines for both of them. Some hydraulic fittings and braided hoses were used to do that. I took the oil feed from front of the block from the main oil gallery and then split it for each turbo by a T-fitting. Main concern was that how much turbos would affect to the oil pressures. But, as I later red from a Allan Allards book, if the turbo or the turbos are ok, it wouldnt be any problem. Pressures dont drop. It is always good to buy a manual or some other informative book after you have already done something?

  How about the intake side? I had bought those two pressurized 48 Dellorto DRLA downdraft carbs for the project, so we had to fabricate our own intake manifold for them. And this was done for the first engine without turbos and we used the same intake later with turbos. I had never used a tig welder and I had never welded aluminum either. But the first time comes to everyone someday. Now was my time! To try and to learn and with such an easy piece as an intake manifold for the V8 engine. After some time and exercise I had done a state of the art (in my mind) intake from aluminum sheets and square tubes. It was not easy for the first timer, but it sure was educational task. How will it work, was another question. Ok, building a pressure box over the carbs was a little bit easier job thought I had already learned how to weld aluminum.

  Intercooler? Of course we were going to use one used Mercedes Benz V8 400 CDI water cooled intercooler that has two inlets and one outlet. In that intercooler the engine coolant takes the exessive heat out of the charge air. If the charge air is something like 130 degrees of celsius (266 F) and the coolant temperature is like 90 degrees (194 F), that cooler drops the intake air to 90 degrees. Not very efficient, but the temperature is kept constantly at the same level. Air to air intercoolers take the heat out very effectively at the speeds or with electrical fans. At the stand still, without fans, the temperature may arise dramatically when turbos do their work. That cooler was a freebie part as it had one dent and was replaced after a collision repair. Small modifications was needed to fit that that piece too, but nothing too hard to handle.

  So, all the bits and pieces were collected and fabricated during the winter of 2007 and it was time to join them together with our Hollow Machine. Ok, we did the first start for the turbo engine at a bench to see if it really starts and runs. It did. At first without boost pressure hoses connected and then with all the hoses connected. Man, it was one exciting moment of my life. And to hear the whistle from the turbos with only 4 inches of exhaust tubes after them. Yeah, it was like a whole baseball team or two whistling after a good looking woman passing by! There is a video on Videos section about those sounds where we drove our Hollow Machine back on trailer.

  So, we then put that new turbo engine to the Hollow Machine and built the panhard rod to hold the front end straight. After some plumbing and tinkering we were ready to go to the first outing of the 2007 season. We had updated the fuel system with a pressure sensing regulator from italian Malpassi and the fuel pump was changed to a Holley blue electric pump. The tuning of the engine was a bit challenging task. To change the jets we had to open all 35 bolts from the top cover of the pressure box. I have to admit that this was a design failure. It looks good, but it doesnt make living easy. The box has a rubber gasket between the cover and between the carbs and it usually holds the pressure inside of the box. Usually means that, when the engine kicks back, black smoke comes out from under the box and sometimes under the intake flanges too. The intake flanges should have been a little more thick material and the warping of thin aluminum during the welding made the intake a bit challenging to seal. Lots of engine silicone was used to help the sealing with original intake gaskets.

  Setting the fuel pressure was also quite hard. If you set it too high, the carbs flooded and when you set it a bit lower, it seemed that it caused a starvation issue. Well, at first we had no idea how big jets we would need and where. So I bought a bagful of jets from a carburetor shop. Dellortos do have idle jets, main jets, air jets, emulsion tubes and accelereration jets to be ghanged by the needs of individual engines and then some progression holes to feed fuel at the acceleration moment. And you can also change the chokes and the auxiliary venturis to various different sizes to make an engine to give its best performance. Quite a mess! With a lots of trials and errors we got this hungry beast running.

  But, it didnt run as we expected. It idled well and took of quite well, but after a while it started running poorly and stumbled. Lots of jet changes again but no significant improvements. It was driveable, so we drove what we drove at the Freak Race on gravel track and loaded things back to trailer. And we went back home to think what went wrong. So, we didnt get much of an information about that weekend, because the track was short and slippery. Although, we made a bunch of people happy with our machine and its sounds.

  We had plenty of time till next event, but we couldnt go to the streets to make any test runs. So we decided to wait until August and the FoMoCo Drag & Track weekend 2007 and then do some more experiments with the Hollow Machine. At August we finally went to Jurva, a race track in the middle of Finland. Things were basically the same as it used to be. We were changing jets with no improvements. The steering was a lot better with that panhard rod and we were hoping to improve our quartermile time by a second or two with the turbos. And when the pressure hose exploded at full speed at the back straight of that Jurva track, we ended back to trailer again. We had no spare hose and we had to go and search one. The feeling was however, that if all things work, we could go fast. We found a way to fix that pressure hose for the next day and the drags at Kauhajoki airfield.

  But, it didnt happen as we thought. Engine stalled right after tree, then picked up again and then it almost shut up again. Damn.... We did several passes with no good results at all. I think 23 seconds and something was the best we could do. We were disappointed and drove the Hollow Machine back to the trailer again. All others were as confused about our poor performance and kept coming asking what was the problem. We didn't know. Then one genious came to us and asked about our fuel pump. What are you using as a fuel pump? Holley blue, we replied. No way man, he said, that is all wrong for charged engines. It only gives a lot of flow but only 0.7 bars (10 psi) of pressure! Think about it, if you have 0.5-1.2 bars (7,2 - 17,4 psi) of boost pressure at the carbs, in which way will the fuel go? Jiihaa...we had not enough fuel in the carbs to go fast. That is the reason. Shit...we are stupid. Didnt even came to my mind that Holley would not be enough to feed our engine.

  Season 2007 was over and we came back home with lots of bright ideas. We bought a Mallory 110FI electric fuel pump which flows up to 72 gallons per hour and gives 100 psi of fuel pressure at max. We also bought a Mallory boost sensing fuel regulator and some AN 8 braided hoses to fix that fuel starvation problem. We got all that installed and Jyrki drove the car to the winter storage. That trip was the last testing session for 2007 and for the first time we felt that "the thing" was working quite right. It was loud, it was fast and it was fun!

  End result after season 2007 was that after all difficulties with setting up the jets for that dual Dellorto set up with turbos was so frustrating that we definetely wanted something new. And the one and only obvious choice was to build an EFI engine. We had seen lots of talking about that subject on the Y-blocks forum, but only few had been done before. A new member, young and talented electrician, Simo joined our Hollow Heads gang during the summer and he was going to build a Megasquirt DIY EFI controlling system for our engine. He had already done one EFI system for his own ‘59 Ford by using Chevrolet TBI parts and Megasquirt DIY box.

  I spent the next winter building up some new stuff for the Hollow Machines trusted turbo engine. New intake manifolds were on the list as we were finally going to build an EFI for the engine. Y-blocks stacked intake ports made building of the intakes very challenging as the plan was to make a true 8-point injection. How to fit the injectors under the runners? I spent hours just thinking the way to make them fit and work on our application. Finally, I ended up to make an angled bits which I then welded to the runners to work as an injector holders. Fuel lines were another hard task to figure out because using a fuel log succeeded only for the upper ones. For the lower ones I had to make separate logs and fit them vertically to connect them to the injectors. Fuel lines made the engine look like an engine out of a WWII tank! But it works!

  Our intake manifolds have two 60 millimeter throttle bodys from 80’s Ford Mustang. One on each side to feed air to the engine. We have only one throttle position sensor at the left manifold because they are moving simultaneously anyway. Also we have only one intake air temperature sensor at the left side. Other sensors that are used in our engine are engine coolant temperature sensor and an O2 sensor which is located at the exhaust down pipe from the turbo.

  New exhaust manifolds were on the list too and this time they would be a bit more flowing ones and connected together as we were going to use only one turbo this time. The outside diameter of the primary tubes is 42 millimeters (1½") and the design is 4 pipes to 1 colletor. After collector the tube dia is 2½ inches and both sides are run under the turbo flange. We had a Rajay turbocharger which was a bit larger than the two installed on the engine and we were going to use it in our Single Turbo Efi Y-Block set up. And this time we will be using a decent wastegate with a 50 millimeter (1.9 ") dia relief valve. A reason for that will be told a bit later on this story!

  Although all the parts for single turbo set up were ready to be installed, we decided not to use them at the driving season opening at a karting track near Kouvola, Finland. There was too many open questions on the air and we wanted to see if the Hollow Machine really was pushing hard with that old twin turbo set up and with that Mallory fuel pump. And because the track was kinda short and narrow, extra power was not needed.

  At the track, in June, however the old problems continued. Couple of plugs fouled and the jetting still wasn't correct. The car had potential and we spun a couple of times during our driving turns but we were not satisfied. I then did several changes to the jetting and finally, after the race itself, we found a combination that was best so far. No hesitation at the take off, no bogging at high speed and we almost flew around the track. Twin turbo was really pulling hard. At one point I was staring at the boost gauge and it was somewhere around 1.2 bars (17,4 psi) of boost at the moment when we were approaching the curve after the main straight and driver Jyrki just kept his foot straight. I had to shout him to slow down or our homemade bucket wouldn't have turned to the curve. Crazy driver, I have to tell you... Seems to be that the small internal wastegates which were now controlled by the Mitsubishi pressure clocks didn't open at the before mentioned 0.6 bar (8,7 psi) boost pressure or then the wastegate holes were not big enough to dump all the necessary exhaust gas to slow the turbos down. 1.2 bars (17,4 psi)....hmmmm!

  Ok, we were a bit happier after that event but after we came back home we started to focus on doing the change to EFI engine. First we put the new intakes and exhausts to our old reliable 272 cid test engine, which was bolted to a storage stand. There we could start it up and see if things are working as was ment to be. All the fuel lines were connected and a wire harness was installed to that engine. The old twin turbo was still on Hollow Machines frame and the fuel feed line from its pressure regulator was routed to EFI fuel lines. Fuel pressure was raised to 3.0 bar ( 42 psi ) to make the injectors work and the pressure hoses from the turbo were left unconnected. A lap top was connected to Megasquirts control box and some testing of the TPS sensor were made and then was the time to start the first finnish 8-point EFI Y-block.

  The whole Hollow Heads gang was witnessing this historical event and taking some pictures and video material about it. At the first start up of this EFI engine we used 19 lbs / hr injectors just to see that if it runs. Then...10 seconds of starting and... What a heck... it runs. It just started idling from the very first moment! Simo had made the fuel charts from some data of his own engine and the rest of it was made by quessing. He was so confused about engine starting right after touching the switch that he was speechless for the first half a minute or so! "Well oh mine oh mine" was all he could say... He had had some difficulties with his own set ups with starting and he just couldn't belive that this kind of a set up would work right away!

  We let the engine idle for a while and then gave it a little more air from the throttle bodys. It hesitated a little but started to raise the revs accordingly. We had no water in the engine to cool it down so we let it run for five minutes or so and stored some data to the computer. And then switched it off. What a success? We let the engine cool down for a while and then started it again without any problems. Man... it works!!! At this point we still had breaker points at the distributor but, after that we had to change those to Crane Xr-i ignition module due ignition disturbanses. The vacuum advance had been taken of the use before the first start up with twin turbo set up and we continued that way with only mechanical advance in use.

  After that first testing day we changed over to 30 lbs / hr fuel injectors to feed more fuel to the engine. It was time to put those efi intakes and new turbo things to Hollow Machine and we had to do some modifications to wirings also. Also, as we previously had two turbos and only one intake hole at the pressure box, we had to change the intercooler line arrangement upside down. Cause now we had only one turbo blowing to two throttle bodies. When everything was connected and the intercooler lines were hooked up, it was time to start that thing again. Now we could run it as long as was needed to make better fuel charts for the engine with the laptop computer. Simo really knows what to do and every stroke of the keyboard made the engine running better and better. Idle was smooth and it took revs rapidly. Small changes to cold start enrichments and we were ready for the Ford Nationals event held at Alastaro 8.-9.8. 2008. And we were really expecting some good results from the quartermile. Well, we knew that our old and tired transmission would probably slip as bad as it did previously, but that wasn't a main thing at the time.

  At Alastaro the weather was a bit rainy and the track was slippery as hell. Our narrow rear tyres lost the traction every time we pushed the pedal deeper down and that caused couple of scary moments for us. Also, Simo was behind the wheel for the first time and he really tried the limits. Once we spun backwards off the track and I (at the moment) was sure that the thing would flip over and with an open cockpit and without safety belts that is not healthy thing to do. But it didn't turn over and we are still alive! That happening is also found from Videos section because Jyrki was driving behind us and Tero was recording it with a video camera.

  But the engine was running perfectly and when there was enough grip it was pulling hard. We gave some experiences to some friends of us by driving around the track with Hollow Machine. Then came the time to try quartermile times. Burn outs went well and it was easy to watch tyres warming up from the open roadster. 60 foot times were at the same 2.7 second range as previously due 2.75 gearing at the rearend and due that 2-speed Mile-O-Matic transmission we were still using. Runs were difficult because sometimes grip got loose after first 60 feet and sometimes after 330 feet and we had to lift off. And of course the tranny slipped. And it slipped bad. Every time it was supposed to change to the second gear it slipped. Sometimes it took the second when we lifted the pedal and sometimes it continued to slip till the end of the quartermile despite of lifting or not. And the times? Jyrki drove the best time of the weekend with 16.658 seconds and 130 km/h (81 mph) speed. I was a little bit slower with my best being 16.919 and with only 115 km/h (71 mph). At Jyrkis best run the tranny shifted to the second gear just before the finish line and that explains the big difference in speeds. I drove all the way at first gear and trying to make it shift to the second by pumping the pedal after it started to slip. It never did...! We did about 12 runs but it was the same every time. Tranny slipped and we were disappointed again. Thought, it scares me to think what would have happened if the tranny had changed rapidly to the second gear just when the boost was at the peak. We would probably have ended to the wall with a broken nose after the tyres got loose!

  Well, what a weekend? We were still alive and the Hollow Machine was still in one piece. The engine is powerful, but how powerful? It felt very strong, but the results don't tell us anything because of that slipping transmission. So, how do we proof what we had made. After a little while and lots of thinking we were all thinking the same. We had to take it to the dyno shop to get some real numbers. So I called the dyno shop and we set the date for the dyno run for 13th of December 2008. And to get as much information as we wanted, I made some new holes to the exhaust pipes.

  At first we were using only one O2 sensor from a Honda Civic and it worked fine. Later, before going to the dyno, we upgraded it to a Bosch wide band sensor which gives us more accurate information and more quickly. That sensor is located at the down pipe after the turbocharger. Now I made two new holes for two more O2 sensors that the dyno shop would use. So now we had O2 sensors at the exhaust manifolds after the collectors on both sides. This is for to control mixtures coming out from both cylinder banks and to see the difference in them. Also, I made a hole just under the turbo attaching flange for the probe to get some data about exhaust back pressures. And that was wise thing to do as we learned later.

  At Alastaro track we still used that 2 to1 water cooled intercooler but for the dyno we changed to one larger air to air intercooler with two electrical fans on it. That would be more effective and now we did not need to think how to fit it to our Hollow Machines frame. I made some new aluminum pressure pipes to connect that new intercooler to our throttle bodies and i also made fittings for the probes to measure the intake air temperatures before and after the intercooler. So, everything was ready for the "D" day.

  13th of December, we were at the dyno shop 9.00 am sharp. It took abot an hour to assemble the engine to the dyno as we had earlier supplied a flywheel and one bellhousing for the dyno man to make necessary modifications to get the engine hooked to the dyno. He had never run a Y-block at the dyno. That is why. Y-blocks are not so common here, you know? And, as the dyno man said, "Who is dumb enough to run and hop up such a piece of shit"! Well, he used to run a Chevy Camaro at the Pro Stock class back in the 80's and early 90's. So he is a Chevy guy anyhow and knows nothing about Ys. He was amazed about Y-blocks stacked intake ports as well... But, he is a real pro at what he is doing, so he can well keep his opinion.

  Ok, the ignition timing was set to 33 degrees and the fuel pressure was set to 3.6 bar (52 psi). The first pull was made with 0.64 (9.3 psi) bar max boost pressure after Simo had tuned up the fuel charts a bit. The first pull gave us 306,7 horse powers at 4800 rpm. Not bad! And the torque? 547,8 Newton meters (403 ft lbs) at 3200 rpm. And the torque was over 500 Nm (360 ft lbs) from 2800 rpm to 4000 rpm. Not bad at all! Even the Chevy guy was stunned now! But he immediately told us some bad news: "Now guys, it seems that your turbocharger is too small. It generates almost one bar (14.5 psi) of exhaust back pressures under the turbo. It just doesn't flow enough!" What? Yes, at 2500 rpm the back pressure is only 0.39 bar (5.6 psi) and it steadily increases to 0.97 bar (14.0 psi) at 5000 rpm which was our limit at the first test.

  For the second pull Simo leaned the mixtures a bit and the hp reading increased to 312,6 hp at 4700 rpm. The torque decreased to 530,2 Nm (390 ft lbs) at 3600 rpm but stayed above 500 Nm from 3200 rpm to 4200 rpm. The boost was the same as at the first pull. Hmmm... Let's tune some more! From the data we could see that the intake air temperatures were very low with maximum readings of 26 degrees celsius (78 F) at 5000 rpm. So our intercooler was working very well indeed. We didn't connect the probe for the before intercooler point, so we don't know what the temperature was there. But, I assume it was well over 100 degrees celsius.

  We did total of eight pulls in three hours and things were almost the same in each pull. For the seventh pull we had raised the boost pressure to maximum of 0.7 bar (10.15 psi) and also we had raised the fuel pressure to 4.47 bar (65 psi) because the 30 lbs / hr fuel injectors couldn't flow any more fuel with the original 3.6 bar (52 psi) pressure we had set at the start. We had richened the mixture again for not to burn the cast pistons. The seventh pull gave us 591.3 newton meters (434 ft lbs) of torque at 3200 rpm and it stayed over 500 Nm for the range from 2600-4600 rpm. Horsepower reading had grown to 329,8 hp at 4900 rpm and the engine gave us over 300 hp from 4100 to 5200 rpm.

  For the last pull we turned the boost adjusting screw a bit further and that made the torque reading to hop over 600 figure. 630,3 Nm (463 ft lbs) at 2600 rpm and 329.5 hp at 4900 rpm. So, every time we added boost, the torque increased and it came at lower rpm levels. Horsepower didn't increase at all at the last two pulls, but the reason for that is in the exhaust back pressures that had grown over one bar to 1.07 bar at 5200 rpm. Damn, I hoped for hp readings over 400 before the day! Anyway, 330 hp and 463 ft lbs ain't bad from over fifty years old iron! And now I know why our old 2-speed slips. I quess it was not designed to withstand that much of torque???

  If you study the hp and torque curves from the dyno sheet, you can see how the torque drops from 2600 rpm to 5200 rpm. It goes down like a horse tail when it should go up and then go down. But the reason for that is obvious. We should have more flowing capasity at the turbine side of the turbo. Or have two similar turbos!

  So, what have we learned about all that what we have done? The efi really is the way to go with turbos. It's so easy and fast to tune with a laptop computer. It don't have to be a high dollar well known brand fuel injection system. A low budget DIY Megasquirt works just fine. Of course it takes time to get used to it and to learn how to tune it, but after that it's easy. With a big engine, you need a big turbo or better yet, two big turbos to get a lot of hp out of it. Torque comes easily, and that is what moves the vehicle. And, you really need a big fuel pump to make enough pressure and flow to feed such an engine!

  What's up next? Well, Hollow Heads are not resting. And the last word at that turbo saga is not said yet. Plans are set to a higher level. We just have to find or buy two bigger turbos and we have to buy more flowing fuel injectors to get more power out of that engine. More power means that we have to strenghten up the bottom end to stand up that heat and beat. That means forged pistons and stronger connecting rods and a balancing of the engine. And some other things too. And all that takes a lot more money than we have used so far to that project. And then we are not playing with the Hollow Machine anymore, because it is dangerous enough with that recent set up!

  Time will tell what happens next. With that Megasquirt system we might end up to use a direct ignition with ignition retard by the knock sensor and ignition retard by the boost pressure. By that way we might use more than 33 degrees of ignition advance without a risk to damage the engine. We may also end up to use a launch control at the starts and maybe even the Anti Lag system to keep the two big turbos spinning fast enough at the starting line.

  At the moment all our energy is focused on to building that Altered Dragster and all engine development is at halt so far. After the dragster is ready for the new engine, we will continue our experiments with turbos and efi systems. Bang Bang.... Until then, OBEY YOUR NEEDS, BOOST IS EVERYTHING!

Story by Seppo






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