Turbo size vs cr ?

[5teve L]

1st off I know it's not a Renault but there are some 2l turbo tuners on here & a few others that know there stuff when it comes to this sort of thing....

I'm going to be looking for a new turbo soon for my car (220 gsi) & I'm looking for around 300bhp with it, now the other thing is, i've been offered a low comp engine as well for a good price, the spec of the engine means it comes out at around 7.6.1 but it won't want to rev very high as the piston/rod weight is quite alot (but it will be strong enough to take 400bhp+ with the right turbo etc.. not that I want that.. )
Thing is I don't really want a really lazy, laggy car on the road so I'm wondering if the turbo choice will help with the low CR & not being able to rev it past 6.5k..
Was thinking maybe something with a .64 rear end with maybe T3 on the front, not sure what size wheels it would need for the power I'd need though..
Anyone got any idea's ?
If I can't find the right unit I'll just build a forged engine instead with either standard CR or slightly higher maybe....
I did wonder if a VNT would be any use but that is an expensive test if it doesn't work..
TIA
Steve

[Scoff]

at a guess 300hp will come up at about 1 bar, which probably isn't enough to warrant compression that low. I don't know what your standard compression is, I'm guessing its 8-8.5:1, you'd want to stick to something like that.

re the turbo, T3 compressor will be too small, you want to be looking at T04E, so T4/T3 hybrid, 50 trim or there about. 0.63ar T3 turbine will work fine.

[Scoff]

Noticed you said 0.64ar, so do you need T25 flanges ? I think you will want 0.82ar T25, 0.64 might strangle it a bit.

[5teve L]

Yeah I think CR is 8.5.1 Chris, can't remember off the top of my head now though.
I will look into turbo sizes & compressor maps I think, I looked at the GT28RS or the 2871 but they are uber expensive at around £850 or so.. thats why I need to get it right from the off..
May just go forged on standard comp then as the forgies should hold ok, it's just the rods tend to be a bit hit & miss to wether they will take up to 300bhp or not & better rods are like £500 so thats a grand for rods & pistons, then you need shells, block boring etc etc, looking at close to £1500 where the low comp 'sherpa' lump is ready to go for £500.... You see my dilema

[Big Jim]

Scoff's right, that CR is a bit on the low side for what you're after, will probably feel a bit lazy. Turbo wise though, sounds like you're describing a std sunny/pulsar gtir T28, think that would be perfect for your needs.

[5teve L]

Hey Jim, yeah I may try a cheapo GTiR unit for now & see how it goes, then if I need more power I can sell the GTiR turbo & buy a GT3071R

BTW I will get you that elbow sometime next week to see if you can sort anything, already some interest in it