Turbocharging a V8, advice
Discussion
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
http://www.mcdeng.co.uk/html/tvr.html
BlownC4 said:
Why quote 4 cylinder engine mods ????? This is all about V8,s , they are very different in the way they make power, 4,s are all about the imaginary BHP figures whereas V8s are about torque, i have absolutely no interest in BHP its a mathamatical equation supposedly derived from torque but never works that way on 4,s simply because they use revs to develope power, V8s use displacement and pure torque to move.
I have friends, with 4 cylinder cars, that will annihilate any car you've ever built.....and Ive no idea what power they have, as quite frankly their owners dont care. Its going fast that matters.An engine is an engine, the same rules apply for making power. And not everything I was referring to was about 4cyl engines.
Everyone has their own ideas....you stick with yours, everyone else can move forward and build more powerful, and efficient engines, of all varieties.
stevieturbo said:
BlownC4 said:
Why quote 4 cylinder engine mods ????? This is all about V8,s , they are very different in the way they make power, 4,s are all about the imaginary BHP figures whereas V8s are about torque, i have absolutely no interest in BHP its a mathamatical equation supposedly derived from torque but never works that way on 4,s simply because they use revs to develope power, V8s use displacement and pure torque to move.
I have friends, with 4 cylinder cars, that will annihilate any car you've ever built.....and Ive no idea what power they have, as quite frankly their owners dont care. Its going fast that matters.An engine is an engine, the same rules apply for making power. And not everything I was referring to was about 4cyl engines.
Everyone has their own ideas....you stick with yours, everyone else can move forward and build more powerful, and efficient engines, of all varieties.
If any of your 4 cylinder friends have a car that they drive everyday week in week out and drag race it , and the vehicle is easily capable of 200mph then i accept the challenge.lol
I only answered a question in the begining, if only we new what this AJP engine was going to be used for?
Still not to worry, i thought that this forum was about petrolheads discussing our hobby and giving advice and learning from others , obviously i was mistaken and its about a handful of ppl who think things MUST be done their way or no way.
You boys carry on ,i shall just watch until the day the inevitable post appears about "today my engine blew" .
Just as a matter of interest how many of you actually drive your high powered modified vehicles everyday,winter summer etc ????
Chillout!
BlownC4 said:
stevieturbo said:
BlownC4 said:
Why quote 4 cylinder engine mods ????? This is all about V8,s , they are very different in the way they make power, 4,s are all about the imaginary BHP figures whereas V8s are about torque, i have absolutely no interest in BHP its a mathamatical equation supposedly derived from torque but never works that way on 4,s simply because they use revs to develope power, V8s use displacement and pure torque to move.
I have friends, with 4 cylinder cars, that will annihilate any car you've ever built.....and Ive no idea what power they have, as quite frankly their owners dont care. Its going fast that matters.An engine is an engine, the same rules apply for making power. And not everything I was referring to was about 4cyl engines.
Everyone has their own ideas....you stick with yours, everyone else can move forward and build more powerful, and efficient engines, of all varieties.
If any of your 4 cylinder friends have a car that they drive everyday week in week out and drag race it , and the vehicle is easily capable of 200mph then i accept the challenge.lol
I only answered a question in the begining, if only we new what this AJP engine was going to be used for?
Still not to worry, i thought that this forum was about petrolheads discussing our hobby and giving advice and learning from others , obviously i was mistaken and its about a handful of ppl who think things MUST be done their way or no way.
You boys carry on ,i shall just watch until the day the inevitable post appears about "today my engine blew" .
Just as a matter of interest how many of you actually drive your high powered modified vehicles everyday,winter summer etc ????
Chillout!
So it isnt just capable...it has actually done it.
There is nothing to be warned about. Everyone has their own ideas. But the reality is, stating that any boosted engine over 10psi must use a CR of about 8.0:1 is just ludicrous.
And when pushing the boundaries, anyone who hasnt blown an engine, clearly isnt going very fast. Its an unfortunate fact of life with reasearch.
Im sure if we all stayed at 8.0:1, and 11psi, we'd all go rather slowly, but very reliably.
Stevie this bit simply isnt true.
Im sure if we all stayed at 8.0:1, and 11psi, we'd all go rather slowly, but very reliably.
I know of many dragcars and hotrods running less boost with this CR and hitting 9.0sec and one in particular this weekend coming will i suspect dip into the 8,s. The low CR gives you reliability you can then add 10 11 12 psi and NoS etc and run consistent low 9 and 8,s ,its not just the motor that makes you go fast, gearing is crucial, last year i ran a 32 model b with a BBB with very little work on the motor to prove this very point, it started in the high 12,s and after many runs ,diff swaps and calculations it ended up runing 10.41 WITHOUT a blower ,BIG cam,NoS or high CR ratio,ON STREET TYRES and not street strip just big wide street only tyres, the one thing it did have was BIG torque as standard, it was normally aspirated using a 750 vac secs holley and open headers ,nothing special, no tricks nothing.The point i was making to quite a few racers was that you dont need to keep banging thousands into an engine to run quick , you need to work clever, match the torque with the gears and you can have a very quick,reliable car without sacrificing reliability.
Now fatjon has stated the vehicle is going to be used for track and strip we have more of a clue as to what spec the engine could go to.
I know your car steve and its very impressive and noway am i doubting or dismissing your or anyone elses experience or comments but Fatjon asked for advice and its all well and good saying you need to have big boost and high CR,s but maybe just maybe he would want good reliable power with longevity without spending thousands.
There are 2 sides to every coin and i was posting my opinion for someone who was apparently new to V8,s.
You have to remember what is was like for you when you first started with v8,s , sometimes we forget the starting point and expect others to jump straight to our level which we are used to and strive to go further but a V8 newbie needs to start gently, it wont take long to catch up as the mods are outhere, much more so than when we started.
Im sure if we all stayed at 8.0:1, and 11psi, we'd all go rather slowly, but very reliably.
I know of many dragcars and hotrods running less boost with this CR and hitting 9.0sec and one in particular this weekend coming will i suspect dip into the 8,s. The low CR gives you reliability you can then add 10 11 12 psi and NoS etc and run consistent low 9 and 8,s ,its not just the motor that makes you go fast, gearing is crucial, last year i ran a 32 model b with a BBB with very little work on the motor to prove this very point, it started in the high 12,s and after many runs ,diff swaps and calculations it ended up runing 10.41 WITHOUT a blower ,BIG cam,NoS or high CR ratio,ON STREET TYRES and not street strip just big wide street only tyres, the one thing it did have was BIG torque as standard, it was normally aspirated using a 750 vac secs holley and open headers ,nothing special, no tricks nothing.The point i was making to quite a few racers was that you dont need to keep banging thousands into an engine to run quick , you need to work clever, match the torque with the gears and you can have a very quick,reliable car without sacrificing reliability.
Now fatjon has stated the vehicle is going to be used for track and strip we have more of a clue as to what spec the engine could go to.
I know your car steve and its very impressive and noway am i doubting or dismissing your or anyone elses experience or comments but Fatjon asked for advice and its all well and good saying you need to have big boost and high CR,s but maybe just maybe he would want good reliable power with longevity without spending thousands.
There are 2 sides to every coin and i was posting my opinion for someone who was apparently new to V8,s.
You have to remember what is was like for you when you first started with v8,s , sometimes we forget the starting point and expect others to jump straight to our level which we are used to and strive to go further but a V8 newbie needs to start gently, it wont take long to catch up as the mods are outhere, much more so than when we started.
lower compression for a daily driver makes even less sense.
Why build a less efficient engine thats going to get used more ??
For a race engine, that may be held flat out for long periods, lower compression may have some benefits.
But for most other applications, as low as 8.0:1, is the territory for a serious high boost engine.
Although in saying that, Ive a friend who runs a 2.0 4cyl with 10.0:1 and 45psi boost.
I dont know how he gets away with it myself !!!!!
Why build a less efficient engine thats going to get used more ??
For a race engine, that may be held flat out for long periods, lower compression may have some benefits.
But for most other applications, as low as 8.0:1, is the territory for a serious high boost engine.
Although in saying that, Ive a friend who runs a 2.0 4cyl with 10.0:1 and 45psi boost.
I dont know how he gets away with it myself !!!!!
stevieturbo said:
Although in saying that, Ive a friend who runs a 2.0 4cyl with 10.0:1 and 45psi boost. I dont know how he gets away with it myself !!!!!
If you're measuring boost pressure in the intake manifold as normal then what you're measuring is how hard you're having to force air into the engine not how much is actually getting in. If it isn't breathing well then you could have masses of boost and still not get much air into the chamber.GreenV8S said:
stevieturbo said:
Although in saying that, Ive a friend who runs a 2.0 4cyl with 10.0:1 and 45psi boost. I dont know how he gets away with it myself !!!!!
If you're measuring boost pressure in the intake manifold as normal then what you're measuring is how hard you're having to force air into the engine not how much is actually getting in. If it isn't breathing well then you could have masses of boost and still not get much air into the chamber.I'll admit some of this is WAY above my experience and knowledge..
But I'll pass on what I've read elsewhere.
The low CR (8.5:1 I think) of the Mustang Cobra (2003/4) appears to be the limiting factor for many race engines. Mostly because they have the blowers running at as high a level as is efficiently sensible, yet the engine will still take more.
A higher CR with less boost would probably see more HP.
The LS engine builders I've spoken to in the US seem to say 9.1:1 CR is good for superchargers and works well with street used turbo setups. The lowest they seem to say use is 8.5:1 but only with BIG turbo's and for such a setup.
But I'll pass on what I've read elsewhere.
The low CR (8.5:1 I think) of the Mustang Cobra (2003/4) appears to be the limiting factor for many race engines. Mostly because they have the blowers running at as high a level as is efficiently sensible, yet the engine will still take more.
A higher CR with less boost would probably see more HP.
The LS engine builders I've spoken to in the US seem to say 9.1:1 CR is good for superchargers and works well with street used turbo setups. The lowest they seem to say use is 8.5:1 but only with BIG turbo's and for such a setup.
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