[jae]

This is quite possibly a dumb question, so let me down easy if I've completely got the wrong end of the stick.

Can steel head gaskets raise the compression on a RB26?

Reason: Turbo lag musings. My pet hate, the lag of the GT-R against the response of the GT-S. GT-S RB25 has higher compression and smaller turbo, therefore, (il)logical deduction, raise compression on RB26, improve response - conceptually valid or horses**t?

 

[polarbearit]

How about using a progressive Nitrous Oxide setup for off boost, say just a 25 or 50 bhp shot when off boost. Should cure the lag problem without expensive and potentially performance damaging engine modifications.

Jon

 

[jae]

Nitrous Aid

Oh, I like the sound of that, but am very wary. Anyone using progressive NOS in a small 25/50 app? (Who was it with the user comment "with just a hint of Nos"? - think he had a white R33.)

 

[Peter]

Lag.

You shouldn't really be experiencing much lag on the stock turbos anyway especially when 'going for it'. It's only when you start sticking larger doubles or singles on that you'll start getting lag. My 2510s aren't really any more laggy than the stock turbos. Have you got a boost controller fitted?

If you do raise the comp now, you'll have to lower it later if you do upgrade your turbos and run higher boost.

All IMHO of course.

 

[jae]

Lagging

No boost controller yet, just wandering around the various possibilities.

There's not much lag per se, it's just I got used to the instant get up & go of the GT-S. It's the one thing I miss. Oh yeah, and the eighteens. But they'll be sorted next bonus, theoretically.

It's all pie in the sky at the moment, but I like to plan the eventual evolution of my beastie.

 

[SkylineNewbie]

SkylineLee has nitrous i think.

Steve

 

[polarbearit]

Alan has the white GTR with N20 I believe.

 

[jae]

Acceleration

Thanks for the pointers, chaps, but after a quick discussion with my good lady, I think I'll wait until I can get F-CON & EVC on the car with R34 turbos and some clever mapping. More reliable and less earache.

 

[hipogtr]

jae... to answer your question (just in case you still want to know the answer), you're right that an increase in compression ratio, all other things equal, will help the turbo spool faster and, consequently, help reduce lag.

However, you won't increase the compression ratio by adding a metal headgasket. You'll do the opposite - reduce it, resulting in less exhaust gas energy, which means more lag (all other things equal). The inherently thicker metal headgaskets increase the proportion of cylinder displacement when the piston is at top dead center to that when the piston is at bottom dead center. Sorry if this is a little technical.

Cya O!

 

[Matt_S]

To increase the CR, the best way to do it would be to skim the head.... but you dont wanna do that.

Spend a few quid on a decent boost controller and you should lose a bit of lag. It allows the boost to cut in a bit quicker too.....

My 2p

 

[jrpidgeon]

There are several things you can do to reduce lag. The last thing you want to do is to increase the compression ratio!, this is a really bad thing to do on a turbocharged car.

There are several options:

1) Fit a boost controller, this will allow the wastegates to open only when the required boost is met.

2) Fitting a programable engine managment system, and have it proffessionly mapped; the operator can tweek the timing at the base of the map; IE add 'small' amounts of advance to the point where the knock is acceptable.

3) The stock cams are an ideal balance of little lag and a progessive power accross the rev range 'from a stock engine that is'. Fitting adjustable vernier pulleys can move the power curve down the rev range a little, this has downsides as the car will probably die off near the end of the revs; but may benefit you as you seem to want the low down torque.

4) NOS is guaranteed to get your turbo's spooling early.

 

[Philip]

If the engine is properly managed, what's wrong with a fairly high compression ratio? You'll have a much nicer-driving engine if you start with one which is decent in normally-aspirated form, instead of something with a 6:1 compression ration and massive boost.

Phil

 

[Syed Shah]

As said, NOS is VERY effective at reducing lag, used often with turbos like the T88H.

But, there are simpler thngs to do: decat + exhaust (the less restrictive the better). THis will reduce lag considerably on a stock-turboed car.

A good EEBC will also help, while things like very large intercoolers will increase lag.

OR, you could get an AEM ECU, complete with an ANTI-LAG program. :smokin:

 

[Matt_S]

If you miss the off boost torque of the GTS, why not just put a GTS lump in ya GTR?

 

[jae]

Funny man

Matt_S

Yuk yuk.

I miss the response, but the ability to go from 0 to in under five seconds is not to be parted with. More mechanicals and the Abbey habit is the answer, pending arrival of large quantities of cash.