2.7 cylinder heads

[PSH]

ORIGINAL: TTM

Interesting Pete... With a high-flowing head it may be worthwhile to use a free-er flowing turbine housing. You should definitely get excellent spool, but probably at the cost of high backpressure robbing you a fair amount of power up top.

Back pressure was my Achilles heal in my last round of mods, this time I plan to cure this, that's why I previously said that the main thing holding me back from 400+bhp before was the exhaust. This time around with the bigger exhaust plus everthing else I'm confident of big gains once bed in and set up again by Wayne. A different Turbo may be added later, I'll see how I get on with the trusty 61 first which btw had been reworked by Turbo Technics and will be again once I get to that stage.

let's hope I'm right...

Pete

 

[Elliot]

I have two 2.7L engines available at the moment if anybody needs one

cheers

 

[333pg333]

ORIGINAL: PSH

The standard Turbo head has both good and bad points in it's design... the Ceramic linings are a good point and as Simon and Thom have said it helps greatly with spool up times but it also has it's Achilles heal which is it's exhaust velocity which is very low at 390 FPS. Normally you can not port the Turbo exhaust ports due to the ceramic lining but Lindsey have found a way around this that means they can greatly increase the FPS while retaining the full benefits of the ceramic liner. My head has an exhaust speed of 566 FPS so you can imagine how this extra 176 FPS, over a standard head at 390 FPS and possibly any other modified head not using Lindsey's High Velocity ports, helps my car achieve it's power output while retaining a very good spool-up speed, I doubt that the lag on my car is any more than a standard 220 using a K26/6 turbo, in fact it may even be less. I have no figures to prove this but can say how the car feels when compared to it's standard set-up. The other good thing about Lindsey HV ports is they don't get carbon'd up like standard ports do so are able to maintain that velocity.

Pete

Pete, I've not seen it termed FPS. I'm told that the stock 951 head flows at 188cfm at .28" and a really well modified 8v head can get up to circa 250cfm. I've not seen a figure for a stock 2.7 head...anyone?
I'm also led to believe that flowbench results can be a little like dynos and not all are created equal so I'm not entirely sure that I take what people publish as an absolute. Not bagging LR or anyone else but a 45% increase seems a little optimistic?
I have always believed that if you modify one link in the chain you are almost have to modify all the links for fear of creating a bottleneck. The final piece to my puzzle will be a custom intake.

 

[PSH]

ORIGINAL: 333pg333


Pete, I've not seen it termed FPS. I'm told that the stock 951 head flows at 188cfm at .28" and a really well modified 8v head can get up to circa 250cfm. I've not seen a figure for a stock 2.7 head...anyone?
I'm also led to believe that flowbench results can be a little like dynos and not all are created equal so I'm not entirely sure that I take what people publish as an absolute. Not bagging LR or anyone else but a 45% increase seems a little optimistic?
I have always believed that if you modify one link in the chain you are almost have to modify all the links for fear of creating a bottleneck. The final piece to my puzzle will be a custom intake.

Hi Patrick

cfm readings are for the flow rate whereas FPS is for the velocity that that flow can travel at , increase FPS you increase spool up and also BHP. You are correct that there's always a compromise, in my case the possible flow is reduced by 3, however the higher velocity that the flow is travelling at makes this of little consequence, ie I'm gaining far more than I'm loosing.
Standard 951 head 188cfm at 390fps
My LR stg2 head 232cfm at 566fps

I can confirm the benefits of this head and my Dyno results would support this, I'm just looking forward to the next batch of Dyno sessions ...

regards


Pete

 

[TTM]

ORIGINAL: 333pg333
I have always believed that if you modify one link in the chain you are almost have to modify all the links for fear of creating a bottleneck.

The thing is, there is always a bottleneck remaining somewhere in the loop, even after having replaced pretty much everything in the chain.
The point is mainly about deciding if it's worth leaving this bottleneck where we placed it when reaching a satisfying balance, or decide to replace further hardware and risk moving the bottleneck to somewhere where the engine's performance is not satisfying anymore, even after adjusting the tune.