Which Stroker Kit

[zia]

if i may comment. air and fuel are the two components needed to produce power by giving the engine larger lungs (stroked) you need the fulfill the requirement of the engine basically giving all the available air to produce given power at certain point. this is where correct matching items come in. if for instance the engine requires 300cfm per min and you have turbo that can only supply 200 cfm the turbo is strangling the engine, it will reach point where it will produce the maximum power per given flow rate and stop.at 5.5k you are bascally only suppling 5psi or similar no where near its requirment therefore the car probably feels dead beyond this point.and lacks power.

zia

 

[J-GTi-R]

Yeah but that would only work if you're asking the turbo to produce more than it is able to. A turbo may be only capable of supplying 200cfm, thus if the engine at a certain state of tune requires a turbo that can produce 300 cfm to produce full power, it will feel strangled once past the limit of the 200 cfm turbo. But if the turbo is set to only produce 150 cfm by your boost controller, then while you're not going to produce the power it should by any means, it won't surely be a restriction to the engine in the way it is on Edd's engine?

 

[Nad]

This is probably wrong as I cant be bothered to read the rest but the restriction in most cases is the turbo at the boost it is running. More boost will supply more air. The stroker requires more air lower down the rev range so the turbo at said boost pressure will max out faster. The head is not a restriction till well over 400bhp, nearer the 500bhp mark. On that note Jun ran 763bhp through a stroked 200sx engine, and how did they get the extra air in there...... well it wasnt major head work as u try fitting much bigger valves in there, there isnt any space, its called big turbo and boost pressure.

Discuss......

Nad

 

[Nad]

Just read a little and would like to comment. J, the theories u have been talking about seemed to be based on an NA engine and would make more sence if they were read that way. Restrictions on NA engines come from not being able to suck enough air in, on a turbo car this isnt as much an issue.

Interesting none the less though and its posts like this that bring around some good discussion.

Nad

 

[memski]

its called big turbo and boost pressure

:lol:

 

[J-GTi-R]

Yeah most of what I've been saying is based on NA tuning, but a lot of it transfers over to forced induction tuning as well, it's just that perfect head flow is not that critical. Overall flow is still very important though, as there is only so much air you can push through an engine.

And I'm still confused about the turbo being the restriction when it's not producing it's peak CFM level, as the same positive manifold pressure is being maintained regardless of the extra air required by the stroker kit. If the turbo was a restriction then surely the boost would drop at high revs as the engine draws more air in than the turbo can supply?

 

[Anonymous]

Try asking Bruce spence where he got his done as iirc his was something like 4" turbo back any decent exhaust maker should be able to make up whatever exhaust you want.
As for back pressure you don't want any on a turbo car do you think all those cars running side exit bloody short exhausts running silly quick times had back pressure built into them :lol:
If back pressure is required its created between the engine and turbo and i'd say there'd be quite abit there already
Maybe even think about having a Rc, Jason Gant style exhaust where it comes out the front of the car :twisted:

DP fabricated the exhaust from stainless and as you say it's a minimum of 100mm/4" from the turbo back.this exhaust is of no use to anybody and i would not rec'd it to anyone who has to drive more than 5 miles in 1 go.it puts a mongoose to shame :evil: :evil: :evil:

apart from that,if you speak to someone from a decent exhaust manufacturer like haywood & scott (sp),they'll tell you that for a 2ltr or even a 2.2ltr,even with a big turbo,cannot flow enough gas to warrant going any bigger than 3"/75mm.

i'm sure if someone would ask nad nicely he'll come up with a formula from 1 of his books for calculating gas flow and exh size req'd.

 

[skiddusmarkus]

And I'm still confused about the turbo being the restriction when it's not producing it's peak CFM level, as the same positive manifold pressure is being maintained regardless of the extra air required by the stroker kit. If the turbo was a restriction then surely the boost would drop at high revs as the engine draws more air in than the turbo can supply?

If Edd's boost controller could increase the boost to say 1bar at higher revs and in 3rd,4th and 5th then I bet it would be ok.AVCR does has this function and I think that's what Edd has.This goes against most tuning methods though as they usually tail the boost off at higher revs or backpressure forces it to drop off anyway.
However Edd is being a good lad(I hope)and not overboosting my ickle T28 :lol: .

 

[Edd]

the only harmful thing i'm doing is using launch control out of every junction :twisted:

 

[GINGA]

Jap performance mag ran a test recently of a 3" exhaust against a 3.5" exhaust on a 300bhp or so impreza and the 3.5" exhaust gained about 12bhp pretty much across the whole rev range iirc and thats on a 300bhp car recon the gains could be alot higher on a 400+ bhp car
There was also a thread going on on passion ford a while back about exhausts where Sean Bicknells 500bhp escos had a 4" exhaust fitted to the car but for whatever reason they had to change the exhaust to a 3" one but found the car to be overfuelling quite alot air to the restriction in airflow using the smaller exhaust created meaning it had to be remapped again.

 

[Edd]

Skiddus us right i could turn the boost up in 5th as i max the injectors low down at about 3500/4000 rpm whereas once at 5000 they aren't maxxed and in 5th gear at 5000revs full throttle its about 80% duty

 

[GINGA]

there you go then set the apexi to gradully increase the boost past the the midrange in all gears 8)

 

[Edd]

no the answer is to fit the 3037

 

[Nad]

Overall flow is still very important though, as there is only so much air you can push through an engine.

Hence why I keep on saying about FMIC pipe runs, that shortest isnt better, but a smooth flow is. Short pipe run may cut out a few hundred rpms lag but will punish further up the rev range.

Also Bruce, the last thing i was trying to calculate from my books was ideal FMIC pipe size for different air requirement based on power wanted as to optimize reduced lag and response, got stuck half way as was coming up with stupid figures.

I think the exhaust sizing would be easier to calculate but I no longer have the book at the moment as have now moved on to racecar mechanics, chassis engineering and handling and finding it more interesting than engines atm.

L8rs

Nad

 

[323GT-R]

What you have to remember here is that a turbo consists of two components (compressor and turbine) that share a common shaft, and so are mechanically linked. Boost pressure may remain constant, but what's happening at the turbine? My guess is if you measured the back pressure in the exhaust manifold (turbine inlet pressure) you would see a sharp rise, and this is why your power levels off or drops at higher rpm. The effect is exagerated by the stroker lit moving more air for less boost pressure.

The turbine is relatively small on the stock turbo, although the housing is relatively large. Moving to a bigger turbo, with more capacity for the increased exhaust flow will definitely have a big effect. Because of the stroker, you should be able to use a larger A/R ratio on the housing than would be possible on a 2 litre, and still see decent response and boost at low rpm.

In terms of headwork, I don't really know enough about the 'R head to comment, however cam selection and timing is something you need to look at carefully, just fitting parts and using settings that work on a 2 litre wont see the full benefit, due to the changed rod length / stroke and bore / stroke ratios.

 

[Crazy]

Well lads I was out in Edds car last night and :shock: :shock: :shock: :shock: :shock: :shock:


FUKC ME!!!!!!!!!! :shock:



I did not feel the turbo tailing off but then again all I could feel was myself FARTING alot and nearly SH!TING myself



This FUKCING thing moves.........................its a beast and that is no exageration as my car pulls 356bhp at 1.2bar and all I can say is that EDDs car would kill mine on take off and around town.


AND ITS STILL ON THE POWER FC BASE MAP AND 0.9BAR :shock:



Edd mate get that 3037 on :twisted:



IT WILL BE EVIL!!! :twisted:


( Edd mate the launch control is :twisted: :twisted: )

 

[Edd]

Booked in for mapping on the 3rd December

 

[Edd]

and cheers for the comments, i'll pay you the bribe money later :lol:

since fitting the powerfc the car wlill pull to 6500 easily now but have the limiter set at 7000 and only ever hit that if i get some wheelspin in 1st gear, eh crazy

 

[Crazy]

Edd

and cheers for the comments, i'll pay you the bribe money later

No probs, forget the bribe mate you can just take me for another blast when its not so dark :shock: and when its not so wet :shock: as at the moment my washing machine is FUKCED and my girl is hand washing my socks and undies but she refused to do the ones I had on last night mate :shock: as they were in a bit of a mess due to your beast :twisted:


Totally blew away with the launch control and as you can see from my sig I plan on getting the PowerFC pro for my car very soon

 

[J-GTi-R]

What you have to remember here is that a turbo consists of two components (compressor and turbine) that share a common shaft, and so are mechanically linked. Boost pressure may remain constant, but what's happening at the turbine? My guess is if you measured the back pressure in the exhaust manifold (turbine inlet pressure) you would see a sharp rise, and this is why your power levels off or drops at higher rpm. The effect is exagerated by the stroker lit moving more air for less boost pressure.

The turbine is relatively small on the stock turbo, although the housing is relatively large. Moving to a bigger turbo, with more capacity for the increased exhaust flow will definitely have a big effect. Because of the stroker, you should be able to use a larger A/R ratio on the housing than would be possible on a 2 litre, and still see decent response and boost at low rpm.

In terms of headwork, I don't really know enough about the 'R head to comment, however cam selection and timing is something you need to look at carefully, just fitting parts and using settings that work on a 2 litre wont see the full benefit, due to the changed rod length / stroke and bore / stroke ratios.

I understand that, and certainly to make the best of the stroker the 3037 or similarly large turbo is a must, but... we're still only talking about 0.8 bar here. I understand that the engine will be shifting more air at the same rpm as a 2.0l, but it's only 10% larger in capacity and assuming the head is not the restriction, then it doesn't make sense that the turbine is restricting air flow when a standard turbo can make 1.2 bar and more without problem (and more air in means more air out, thus the back pressure in the exhaust manifold will be much greater as a result of the increased boost).