Turbocharging a V8, advice

[fatjon]

Just setting to work on turbocharging an AJP V8 and could use some advice from anyone who has done a V engine before. Simple question, 1 big turbo or a pair of small ones. Way I see it is that small ones spool faster but if you hit a big one with twice as much exhaust flow it should spool pretty quick, cost less and the pipework is a hell of a lot easier. Have retrofitted a lot of 4 pot engines with turbochargers but this is our first V engine project. Advice from anyone with experience would be very welcome.

FatJon

[fatjon]

I have a cerbera but this engine is not going in it. We are building a proper thunder saloon from a Vauxhall Omega. The turbo(s) will be in front of the engine as I am keeping in mind that once the system is up and working we may want to try and graft it into the Cerbera or at least have paterns for the manifolds to then do the Cerb. I think if the turbo is kept high, roughly at the height of where the aircon pump is mounted (but forward) it should go in the Cerb with minimal mods. Heat control would be the challenge in the TVR body rather than the mechanics of fitting it all in.

If trackcar=jules in Chesterfield see you on the 12th!

Jon

[fatjon]

I'm leaning heavily towards the single turbo option, anyone want to convince me otherwise? The more I think about lambda measurement, wastegates and boost control the more the twin option looks like a real PITA.

Jon

[fatjon]

Boosted LS1 said:

I had a call about a racing project like this a couple of weeks ago, is Derek involved or is that a totally different project? Just curious:

From a racing perspective I'd go with one large turbo if you plan to be on boost most of the time and if it's easier to install.

Edited by Boosted LS1 on Thursday 28th August 22:16

I don't know anyone by that name so it looks like there is another set of madmen around somewhere! The original plan was to drop the engine in a single seater but lets face it, that's suicidal. The only people I have discussed it with in the TVR circle is a chap at clever trevor who is looking into supplying a custom paddle clutch assembly and flywheel.

Jon

[fatjon]

I'll be early. I need all the help I can get with this damned MBE. I've put the cerb away for a while and running round in one of the other motors so you can have it as long as you need it, no hurry at all.

Jon

[fatjon]

chuntington101 said:

any reason you have picked the AJP V8 for forced induction??

as long as the turbo(s) are matched to the engine and power requierments then it shouldn't matter if it twins or single.

sounds like a very intresting porject. cant wait to hear more about it.

Chris.

Several reasons why I picked the AJP.

1 it's never been done before so far as I know.
2 if it can make 95BHP/litre without a turbo it has a head start over some yankee crossplane
3 it weighs about the same as a slightly damp feather
4 it's very compact
5 if I drop the RPM ceiling from 7500 to 6800 and get 750BHP it should be very reliable as it will not be highly stressed on the exhaust stroke and not near its rev limit.

There are also a few good reasons not to use an AJP though, like custom pistons to drop the compression, a custom plenum for a single throttle body, its odd firing angles and the cost of the engine. I'm gambling that I can open up the combustion chambers in the head and rework the crowns to get down to maybe 8.6:1 then run maybe 1.5 bar without custom pistons. Either way if we need pistons it's not disaster. Accralite can do a full set to the original dimensions for £880 so to lower the crown a mm or 2 should not be significantly more expensive.

Jon

[fatjon]

Will have to see what can be done without compromising the crown strength. I may be able to get some meat out of the chambers in the head but if it needs pistons so be it. Got the engine under the bonnet today for a test fit. The car could have been designed for it! Loads of room around it and the engine sits well back. Even the gear lever is just a couple of inches from the original location. Because of the sump being offset to the drivers side with all the ancilliaries together there is loads of room on the nearside for a huge exhaust. The test fit has relieved a couple of worries, like clearing the x member and steering box. All in all fitting it's going to quite easy. Will fabricate all the mounts and then remove the engine for its rebuild and mods. The plenum, fual rail and throttle body assembly will all need to be hand made. I reckon that will be among the more challenging bits of the job. The more I look it the less it seems possible that it would ever go in a Cerbera though, but we shall see! Pics to come later.

Jon

[fatjon]

Having had a look at the credentials mssrs Boosted Ls1 and Stevie Turbo I reckon that I will take their well qualified advice and have a new set of pistons made. I suppose on the scale of the rest of the budget for the project the pistons are not going to be the biggest cost compared with potentially trashing an AJP with a piston failure. I've learned over the years of building silly cars is that everytime you cut a corner it will come back and bite you in the wallet so thanks for the reminder!


Jon

[fatjon]

Its very much in the tuning and accurate ignition control. I have a Maestro 16V turbo which runs 24PSI at 8.5:1 and has no problems making a reliable 440BHP with water injection, without it I'm quite sure it would explode. My magnum runs 28PSI at 8:1 without WI but I run it rather rich at high boost. I don't think the bottom end needs much work. The AJP was designed to make much more than TVR ever extracted from it.

Jon

[fatjon]

I was trying to be diplomatic :-)

[fatjon]

Just a minor correction. The AJP is not a heavily reworked Rover V8. It's a totally unique all alloy flat plane crank screaming racer. It was originally designed by MCD (Al Melling) for a Lola F1 car but they went bust and it was reworked/detuned for TVR and used only in the Cerbera and Tuscan racer. It was not replaced by the speed6 engine as such, for some years both were available but the production costs of the V8 meant TVR dropped it and carried on only with the less powerful S6 engine. The 4.2 AJP makes around 360BHP and the 4.5 a quoted 420BHP. In reality the only way to get above 400 with the 4.5 is to rework the engine management. Because of the basic F1 layout of the AJP it weighs in at 140Kg fully dressed, revs to 8Krpm and has huge potential for even higher power outputs. The 4.5 propels a Cerbera to 60 in 3.8 seconds and on to 190Mph+ so definitely not to be confused with a Rover V8!

http://www.mcdeng.co.uk/html/tvr.html

[fatjon]

track days and drag strip only. it's going in an omega shell