New poster! (less than 10 posts)
Hi,
I'd just thought id post on here and try and pick some brains.. also posted on renault5gtturbo forum, guys on there have been pretty helpful
I've been rebuilding one of the original cup cars (radbourne 003) for the Toyo Tires saloon car championships next year. Fairly familiar with building race engines (and cars) as have been doing it for a while.
Due to the technical regulations i'm constrained from going down a traditional tuning route with the 5. In short I have to stick with the standard Turbo (T2 with the addition of a 360 thrust bearing - tubby has to be inspected and sealed so no chance at ALL of a sneaky hybrid) and standard management (though the advance trick will be fine, and standard fuel delivery (hence the grp A carb is ok, but I cant go standalone management and injection
My car runs around the 160bhp mark at the moment, but I want more!
I know that the works Renault 11 rally cars (same engine and turbo) used to run close on 180bhp with a fairly standard engine but grp A cam.
From what I understand this is about the max air/bhp the turbo can flow and headwork and larger inlet valves will make little if not any extra power. Also its looking like a 285 profile cam could really hurt performance running a standard T2 as its moving the power band of the engine up, whereas the T2's powerband is lower down and is running out of 'puff' by 6'000-7'000 rpm if not a bit before.
Have spoken to Cat Cams who pretty much confirmed that, and they are looking into doing me a custom profile to compliment the power curve that the T2 produces.. does this sound about right?
Originally I was considering putting together a completely balanced bottom end, together with hot cam, massively worked head, with work done to the throats, valve guides, enlarged inlets and bigger inlet valves, uprated springs etc, etc.. tubular manifold, tubular turbo back outlet pipe.. In short the type of engine you would build if you were considering putting a hybrid on for serious bhp. From experience I know that putting a really decent, worked head on a car should give around a 20% power gain, but there seems to be an upper power celing with the standard T2 of about 175-180bhp, so this is looking like throwing good money away?
Obviously every extra hp I can get counts, but don't want to spend £800-900 on a head and £££ on other bits and peices if its not going to do get me any further than the 180bhp barrier so its now looking like a Quaife ATB diff is going to be a better investment..
If anyone has any experience or hints on what to look into to squeeze more hp out id really appreciate the help.
Also has anyone flow tested the heads that GT Tuning and KTec produce, as they seem to be half the price of the same head that Prima produces (i've seem the flow graphs for the Prima head as well and is a seriously well done head..) but again, am always up for saving £££ if the product is good!
Cheers
Oli