Engine and Transmission Tech

I have been playing around with the idea of a turbo for one of my TR8s, after seeing several stroker motors with disappointing HP per dollar ratios. Originally I was going to put two small turbos in the engine bay. I picked up 2 KKK turbos from the VW 1.8 turbo and started to make the turbo exhaust manifolds. I'm starting to rethink my approach because the engine bay is so crowded and the fab work isn't exactly easy. What if I just use the tube headers I all ready have and y the exhaust together into one pipe. I can mount one large turbo where the gas tank is/was, and run the charged air back to the engine. I have seen some impressive numbers put up with this set up on other cars. I plan on using a 4.0 with 3.5 heads to lower the compression. My thinking is use the 4.0 front cover with the crank driven oil pump, and the 4.0 intake. I'll probably need to replace the stock injectors and throttle body with bigger Ford units and run either megasquirt or some other more expensive engine management system. I will also have to run some kind of pump to get the oil to the turbo and back. My guess is that this could be done for much less than the 7 grand plus it would cost to build a stoker motor, should put out more HP, and would also be more sedate than the big HP stroker motors out there. What do you guys think? Any thing I'm missing here. This is the car I want to put it in.

I've done a little digging on this. I think it's a great idea. It also distributes the weight a LOT better. If I go to forced induction I was thinking of trying this. The two 3k turbos would work too, I figure but twice the plumbing... Might want to go with the single. Less work.

Your standard hot wire throttle body should be fine I'd think. Since it's a mass airflow system it will continue to measure the condensed air and will allow a higher flow due to the increased pressure. Bigger injectors of course.

Jim

Todd, like any skilled build, you need some realistic spec's-lots. Depending upon boost, you may need to upgrade to stainless exhaust? You don't like superchargers because? The newer- screw types are quite efficient and will give boost,"now", and they don't try to melt everything around them. If you need lower comp. ratio, 300 heads will do the trick, and definatley flow more.Good Luck, roverman.

I have been considering the idea of the Remote turbo (rear placed turbo) over the last year or longer but have had no time. My plans is to start with extreme low boost, say 3-4 PSI on a stock PCM (3.4L V6 SFI MGB) and build it up from there. It will not take much before a complete computer retune will be needed but I want to see the limits of the factory settings with minor mods just for info for others to follow.

There are a few dyno videos of cars that have had this done and I was surprised to find there have already been 3.4L V6 motors with rear turbos. Search youtube.com for rear turbo... I like the idea and will start cheap- when i get time and the suspension upgrades have been completed.

-BMC.

As many of you all ready know, the cylinder heads are by far and away the limiting factor in making horsepower in the Rover V8. Anything over 280 at the wheels is a major and expensive undertaking. Add a turbo and the cylinder head goes out of the equation. 400 at the wheels becomes a very attainable number without even touching the heads. My plan is to run around 10PSI of boost into an otherwise fairly stock motor. I'll make use of a bunch of the pieces I have laying around here, including cams, headers, heads, motors, intakes, etc. I used to race a TR8 in the SCCA, so I have a garage full of pieces that I could not use on the race cars because of the rule book. The big expense will be the engine management system, injectors, and a good turbo. The fabrication work required to do this isn't much more than building a fancy exhaust system. A forward mount system requires building custom tubular manifolds for each side. I started down that road, and it quickly became apparent that it would be too much work. The 4.0 with the 3.5 heads will drop the compression back down to around 8 to 1, which is perfect for a turbo, and I just so happen to have 2 spare sets of reworked 3.5 heads sitting on a shelf. The 300 heads would drop it more than what is necessary. I still have a decision to make on the block. I have a good used 4.0 and a new crate motor 4.0 that was installed in a car and barely broken in. Should I use one of those, or send another out to be rebuilt with forged pistons? My thinking is put in the used one and see what it takes to blow it up and then go from there.

Todd,

You need to look at the corvette guys. They all mount the turbos in the rear like you said because there is no room in the engine bay and run the plumbing through the body work or under panels.

Todd, your piston choice depends on how much boost you'll run, and as you'll find out the heads do eventually limit power output. This is not necessarily a bad thing, but as you continue to build pressure to get past the head restrictions you work your way into the less efficient areas of your turbo's performance envelope and begin to build more heat which obviously works against you. I was able to get around 300 hp out of a 215 running 16 psi of manifold pressure with an Eaton blower and an intercooler (8.5 static compression) but began to see erosion of the top ring land of one of the stock pistons.

With the lower compression come some things you might not care for so much. Poor economy tops the list followed closely by lower bottom end torque and slower response. For my current build I have chosen to follow Oldsmobile's lead and begin with higher static compression and use less boost. You can pick up the details of that on my 340 thread in the MG section.

I'm not a big fan of turbos but have to admit they have gotten better. My turbo motor was real bad about putting the car sideways at the most inopportune times. Regardless, the rear turbo has gained some favor but I have heard at least one negative comment about it. I don't remember where or what though so I recommend you do your homework before you start. Personally, I like the Eaton blowers. Bill Jacobson has a very clean build that the hood closes on, and for that approach I would build a long runner EFI intake with an underslung M-90 or M-112. That approach would also allow an air/air intercooler if you wanted.

I don't know what your horsepower goals are, you were talking some pretty big numbers. Anything between 200 and 300 flywheel horsepower makes for a very nimble car and over 300 is generally conspicuous consumption (wretched excess) but there are a few of us who've been bitten by that bug and I'm guessing you're one too. I'm a big fan of the forced induction approach for reasons you named, so good luck with your build. At the power levels you seem to be looking for I suspect forged pistons are the logical choice.

Jim

Hoping for 300 to 325 at the wheels with a 4.0 on 10 pounds of boost. Nothing crazy needed on a sub 2400 pound car. Mathematically it works. Now I just need to find an appropriate single turbo, EMS, and injectors to use. I spent some time doing the math and looking over turbo graphs to pick the previously mentioned twin turbos, so picking a single larger turbo shouldn't be difficult. Anybody have a use for two KKK turbos? I've been trolling the turbo sites to soak up as much knowledge as I can to help see me thru the whole fuel injection engine management thing. I have been picking Tim Lanocha's brain about this stuff. He has experience with both and also wants to do a similar project. I just wish there was some local know it all kid that this would be second nature to. All of my buddies are old school carb guys, except the Porsche guys, and all they know how to do is write checks. Once cruise night season starts up again, I should be able to find someone local to help with the techy stuff. Until then I'll just start on the easy stuff, and continue to gather the rest of the pieces.

Todd, I don't know what your 3.5 heads flow, but initially, those hp. figures look a little optimistic? I think I'm with Jim on this one regarding, hp/$/labor. Good Luck, roverman.

A normally aspirated 4.0 can put out 240 wheel HP with standard treatment. I've seen flywheel dyno figures of 300 on at least a couple of modestly built 4.0s. Tim got 280 plus on that 4.020 bore motor that Mike posted pics of in a previous thread using a 3.5 crank. That is before the engine let go and the motor started pressurizing the cooling system. That motor was in Zach Torman's yellow car- briefly. Why would you think 300 would be overly optimistic using forced induction? Ask any turbo guy and they will tell you the last place to look for HP on a turbo motor is the heads. The main reason I am looking at this route is to overcome the limitations created by the heads. Jim claimed above that he got 300 out of a 3.5, and that is using a supercharger. By design, there is more parasitic power lose using a blower over a turbo. The fabrication work involved in this build should be a piece of cake. Here are a few pics of the roll cage I just finished in my BMW 2002. I will admit thou, this is definitely unfamiliar territory for me. Give me Weber DCOEs, SUs, or a four barrel Holley any day. I am really looking forward to using the distributor-less ignition and crank driven oil pump. On the TR8 race car, the cam gear and distributor drive gear were always an issue with wear problems. Seems that there just isn't enough oil up there for sustained high revs.

Ok, so on the 4.020" bore motor,(Mikes post), looks like a crossbolt block? The trick for using a 3.5 crank is...bearing spacers? What is your parasitic loss % for motor vs. rear wheel ? 3.5L Jet Fires made approx.200 hp.(flywheel, with accessories), on 6 psi boost. Even though that turbo looks primitive by todays standards,You can ask Jim Stabe how well they worked, when he cranked-up the boost, and they were the "First", mass sale/use in US gas powered pass cars. Similar flowing heads with better valve locations. Why will yours be so much more productive ? Regards, roverman.



Edited 1 time(s). Last edit at 01/19/2010 09:18PM by roverman.

Good point on the pictures Mike posted. I'm going from memory here. I delivered the broken car with that motor back to Tim a year and a half ago. We had the conversation in his driveway concerning the specs on that motor and then another one this year at Carlisle. I do remember him saying it worked out to 4.2 or 4.4 liters, so it must have been a 4.0 crank. I just emailed him, so I'll ask him again when he gets back to me. I don't think he has abandoned playing around with the larger bore motor. The problems he had were with the heads. He wanted the larger bore not for increased displacement, but so he had room to fit much larger(chevy?) valves . This required substantial welding and redrilling in the heads. That is where the water jacket cracked. It all goes back to the heads being the limiting factor for these motors. I believe the Jet fire was rated at 215 HP with no intercooler utilizing a carb with water injection to retard detonation and cool charge temps. There is a complete Jet fire turbo set up in my buddies basement. Real primitive looking. I don't know what I am going to end up with for power. I do know it will be substantially more than if it didn't have a turbo forcing air and fuel down it's throat. All I can do is guess until it's done. Then I will know if it is possible to get 300 wheel HP out of a 4.0 liter running 10psi of boost with an intercooler, fuel injection, and a sophisticated engine management system. Normally aspirated, a Rover V8 can't have much more than an 85% volumetric efficiency. At higher rpms where you get the highest HP numbers, I'd bet it drops to 70% or less as it is struggling to get air into the chambers. The only force drawing the mixture in is atmospheric pressure rushing to fill a vacuum created by the piston traveling downward in the bore. In order to fill that vacuum, the air has to travel past all kinds of things trying to slow it down. With forced induction, throw that out the window. Instead of fighting to get that extra ounce of air fuel mixture into the engine, it now becomes how many pounds of air fuel do you want to push in. The power created is directly related to how much air and fuel you ignite and how efficiently, and completely it burns. Stop and think about how much more water you get out of a hose if the pressure increases, and water can't be compressed. Air can, and compressed air occupying a given volume weighs more than non compressed air. More air- more fuel- more power. Yes it will generate more heat. Yes there will be many things that bring the theoretical HP numbers down to real world measurable numbers. And yes I will blow it up. I am a big fan of catastrophic failures. That is why I have more than one race car. Maybe Mike can post a pic of the Last TR8 I stuffed into a wall on the race track. A rough calculation nets a potential of just over 40 pounds of air/minute given the above specs using an intake charge density of atmosheric plus 10PSI calculated at 130* F. Very reasonable temp assumption given the location of the turbo and the intercooler. That amount of air and subsequent added fuel has the potential to make over 450 HP before you start with the parasites. Any more calculations than that and I will have to go get a calculator and look up some formulas. It's been 25 years since engineering school. I need to spend some more time plotting points on turbo compressor graphs to figure out which turbo will work best- theoretically speaking. Man I wish someone else had all ready done this, and I could just write a check for a kit.

No kidding. That's how I feel about my intercooler right now. Todd, I think you can get that much power out of it. Whether or not it's a Dixie cup is an unknown, but like the 4.020 motor, you're sure to find out one way or the other. Properly done, I think it can live.

A few facts about that 300 hp blower motor. First, I wanted to avoid blowing it up right away so I used a stock Jetfire cam. I also used Olds heads. That right there should tell you that your target is within reach as far as flow potential is concerned. You may have to run more boost than you plan, but a bigger cam will surely help. My limiting factor was the cam and the port flow, and in the upper rpm band boost pegged my 16 psi gage. Doesn't mean 16 psi was getting in the cylinder though. But that is double the pressure that the stock engine saw and 10 psi over the Jetfire, with everything else except the CR being the same. It was a beast, but the rods, crank, and everything except that piston edge held up fine, aside from the head gaskets. This time, with the 340 I'm going with copper and o-rings, and 10.6 CR. Plus boost.

So you're in good company here. I'd suggest you be very careful to do everything you can to eliminate turbo lag. With my Jetfire (with custom header and fed with a 2" SU) lag was a problem and it caused me to wreck it twice, both times on the freeway and both times involving other cars. It was especially treacherous on ice. I've not had those problems with the blower.

Jim

Quote:

Tim got 280 plus on that 4.020 bore motor that Mike posted pics of in a previous thread using a 3.5 crank. That is before the engine let go and the motor started pressurizing the cooling system.

@#$%&. Sorry, Mike. High hopes, no luck. I really appreciate the proof of concept though. Way to go.

Nix- No big deal. The motor should be good to go for dyno runs in about 4 to 5 weeks just waiting on some parts. This will a true test and then I will find out what was done for sleeves and well extras for sure. If it works well my rally car will be getting the same engine! with the 3.5 crank since I have a 4.2 liter max limit! As Todd mentioned the heads will as usual be the weak link but forced induction may "blow" that theory!

Yesterday was a good day. I tore apart the 4.0 junk yard motor I picked up last Summer. Looks like that was $150 well spent. The plan was to use the timing cover and intake from the junk yard 4.0 and put in on the 4.0 crate motor I have, but after seeing how nice the inside of this one is, I might just use the junk yard motor. Tomorrow it goes to a machine shop to be officially checked out. Maybe I can just get away with some new gapless rings and new bearings. A local VW turbo guy came by the house last night and we had a long talk about turbos. He knows his stuff and was able to point me in the right direction. By the end of next week, I should have the turbo, and EMS picked out and ordered. I have a ratty looking, but very solid TR7 coupe that has just been sitting here. Over the weekend, I will gut the TR7 and install the subframe and other pieces necessary to put the v8 into it. I can build everything up on that car and not have to worry about damaging a car that is all ready done cosmetically. Does anybody know the stock cam specs for the 4.0? I have to pick out a cam with no overlap, a lobe center of 114-117 and ideally one with a longer duration for the exhaust than the intake. The stock cam may fit the bill.

Finding that zero overlap will be the challenge. I know some people have been running them, including some of the turboBuick guys and they would be a good resource for your build as they have kept pace with all the new stuff. For instance, they could tell you how that cam is going to run, and what the Buick motor likes in terms of lift, duration, etc. Dual pattern cams aren't exactly scarce but a turbo pattern for your motor may not be common and you may need help finding it.

Jim