right just wondering if there is a point with a high comp engines where you hit a power limit because you have to lay on shit loads of retard to prevent detonation as the boost increases with engines around 9.5:1 compared to a low comp engine mapped with more advance at the same boost

its just im shure my zetec felt faster with the decomp plate on (7.7:1C/R)at the same boost compared to now with just focus rs gasket fitted at (9.5:1C/R) even though the car was remapped

 

Yes absolutely, too high a CR means you have to retard the timing so much you end up gaining nothing from more boost.

HOWEVER, the higher your RPM gets, the higher the "workable" CR at any given boost value is.


So its a triangle really, of boost vs rpm vs CR

And there is a different triangle for each fuel you use, if you are on 102ron then 9:1 is nothing even at big boost at moderate RPM

 

the moral of the story is that unless you got race fuel, high comp turbo engines suck penis unless you got a car with a mega high rpm peak power and dont mind not having any lower down punch.

 

For FWD its great, you can make the power more progressively.


Thats why on my car im running 8.2:1 compression to make 500bhp+ on pump fuel hopefully, but i will be doing it well over 8Krpm

If i was going for 500bhp in a cossie, i would want the torque to go with it as you have the grip and the weight pressing down on the tyres etc, so i would got mid 7s or less on compression and make it at less rpm.

 

I just read in a jap car mag that some old shedder jap car that it runs 14:1 comp ratio and 65psi and "only" produces 600bhp is this because of this?
Fuck knows why I bought a jap car mag its just there was this r32 that looked like steves on the front and i liked it.

 

14:1 and 65psi?

Must be running some SERIOUS fuel.

As for why it only makes 600bhp, maybe its a 1300cc engine or something?


If its a skyline its certianly not pulling the numbers

 

wild cams help on higher comp.

 

Maybe that 14:1 and 65psi is a diesel?

sounds spot on for that

 

Good point, didnt think of it from a traction point of view, in that case, fuck the torque, just a long progressive powerband to ride is a good plan

 

not again

you low comp engine will feel faster cause you need to pump more boost into it de overcome the fookin lag you have off boost, hence when it comes in hard it WILL feel faster !

as for retarding the ignition loads, no matter how you make your engine work at some point you will need to back the ign off, wether it be due to high compression and x boost or low compression and x boost

just all depends on what x=

 

No, METHANOL . so just like a normal road engine then (I have the same mag).

It also has all the water ways filled with resin (to stop the flex) as it only runs for 9s at a time (plus line time).

 

I thought it was race fuel Mike?

 

The 400bhp engine was on race fuel, the 600bhp one on methanol.

 

What engine we on about?

Must be fookin tiny to need methanol and boost like that for such little power

On that note, heres a GT42R on a lil honda lump

 

Cheers Mike Ill read it properly later tonight.

 

what are you doing online at this time of day mike?

 

there you go chip, a home for your new friend

is it me, or is that inlet from chargecooler to plenum a bit small?

 

Steve,
Is a Nissan SR20DET engine in a Datsun 120Y - does 9s quarters at 140 mph (400bhp @ wheels) in this month's Banzai. New engine is aiming for 600bhp @ wheels and 7-8s quarters at 160mph.

Nick,
Jen is watching the figure skating, and I would rather watch paint dry. As we haven't got any paint for me to apply, I thought I would come on here to amuse myself for a while .

 

Nick, its met my honda engine once before, i was seriously contemplating it, lol



Shame thieves had other ideas

 

my missus is watching that shit too

 

Sounds a very OTT spec TBH mike, but if its drag only, i guess they dont care.
SR20s are capable of similar power as YB's with similar amount of mods.