WHAT TURBO IS BEST TO REPLACE RS2's?

[GazzaG60]

depends on size really. the one i have boosts from about 3krpm but its about 4 when it really starts to wake up. boost till whenever.

the sc61 was a very popular choice for the honda guys a few years ago. that was on 1.6 and 1.8 motors in general. thing is their motors are far superior to ours. head flow is what its about really. they used to boost them from around the 4-5k mark up to the high nines. its a 9-10sec turbo for them. i bought it to fit to the corrado which was a 2l 16v i was looking for 450whp on the 2l. probly gain around 300-500rpm spool over the 9a.

on the newer precisions. not sure. still trying to work out how i get a V-band on the manifold and in all honesty i may wait till i can be fekked with a new downpipe etc etc.

but like my turbo guy says there is not a lot wrong with the SC61 so if its not broken why try to fix it.

[prosty]

Yes the heads are the bottleneck on our great sounding engines. The first thing you need to do after ~400+ hp is the mira-machine your valve seats, after that you can go up to ~600 hp without having to port the cylinder head itself.

[audiman]

mira-machine your valve seats

What is that??

I ran a lightly ported head on mine which was 600+bhp, valve seats i left stock as i didnt want to risk them burning easily.

[david]

Yes the heads are the bottleneck on our great sounding engines. The first thing you need to do after ~400+ hp is the mira-machine your valve seats, after that you can go up to ~600 hp without having to port the cylinder head itself.

what is that involve?

[GazzaG60]

is mira-machine mirror machining ie polishing of seats

slightly off topic not sure what im to do head wise if anything at the moment. i planned a cncheads custom 16v head. what ric wood doesn't know about porting is not worth knowing. it was 1400 quid though. gonna be about 1700 for the 5 pot. big valves on the exhaust side and some nifty port work. was looking to make a solid lifter high hp 16v though with some room for margin/extra power.ric did a supertourer once. made 504hp at 1 bar boost. good flow.

[A80Avant]

Honda's and Mitsubishi's have been using succesfully a lot of holsets so far without any problems with them being for diesels.

Billman is hitting 1.7bar @ 4000rpm with his HX40 on 3d gear which is quite remarkable if you think about it,since it has a 64/74mm turbine wheel (on a machined RS2 hotside of course)

anyone knows the AR of the RS2 hotside?

[Jamo]

Precision seems to be popular with the yanks http://www.motorgeek.com/phpBB2/view...0408fc2258bed8

Frankly pays your money takes your choice

[prosty]

Dunno if that is the correct term, but machine work on your valve seats, making a bigger angle, mira grinding / machining.... The biggest flowstopper isn't the exhaust / intake channels, it's the valve flow

However one thing doesn't exclude another, always good to have a machined / ported head , but more important to have increased flow at the the valves.

[UUUdirs2newcastle]

Dunno if that is the correct term, but machine work on your valve seats, making a bigger angle, mira grinding / machining.... The biggest flowstopper isn't the exhaust / intake channels, it's the valve flow

However one thing doesn't exclude another, always good to have a machined / ported head , but more important to have increased flow at the the valves.

So standard valves, but Mira-Machining the seats and a 'ported/flowed' head will help a fully Re Mapped & Tuned engine perform massive results?

[GazzaG60]

basically when you get thye air for around 400 flowing in the head its nearing capacity for extracting efficient power. you end up with a build up of air and it cant get into the cylinders. a cam with a higher lift enables more air in and a port and polish will increase the amount of flow possible at any given lift. what this in turn does with a turbo engine is feed it more air. the turbo still hits say 1.4bar but to attain that it takes more air as there is more room.

add more fuel and hey

have a look at a 16v head on cncheads.co.uk it will give you the idea. they are the same as ours +1 pot.

[david]

Rs2 conversion

basically when you get thye air for around 400 flowing in the head its nearing capacity for extracting efficient power. you end up with a build up of air and it cant get into the cylinders. a cam with a higher lift enables more air in and a port and polish will increase the amount of flow possible at any given lift. what this in turn does with a turbo engine is feed it more air. the turbo still hits say 1.4bar but to attain that it takes more air as there is more room.

add more fuel and hey

have a look at a 16v head on cncheads.co.uk it will give you the idea. they are the same as ours +1 pot.

can this be done to 3B head and have thesame result, as i will have a spare engine once the conversion is done?

[GazzaG60]

a 16v head is basically the same. add 1 pot. the difference is the water rail. ther isn't one on the 16v.

the finish on cncheads site will be what an i5 head would turn out like if thats what you mean.

there work is top notch but not cheap. IIRC they quoted me 1400 quid to do the 16v head to my spec.

to be honest the the heads can flow for 400hp. i would not be going to cnc if i wanted less than 600hp. i see them in that band of elite/ cost versus power bracket

[Error404]

You can get a pretty reasonable gain with a DIY port match and decent 3 or more angle seat cut as I think Prosty said earlier in this thread... its that extra little bit of work on the tunnels and the expertise around a particular head that really only an expert can extract - but as you say Gazza the cost isnt really worth it unless going for big power

[GazzaG60]

porting is specialist. i dont feel its necessary to have a make specialist just an airflow specialist. a flowbench tells them where the issues are.

one thing to rememebr is gas speed is all important. a syuper port and cam job helps extract that extra hp but like most things its a trade off and often low end is affected and porrer performance as a result unless in the newly found powerband.

a quick diy port can help but are we causing issues by not being sure and able to match ports effectively enough?

[Error404]

i meant port matching in terms of matching head ports to IM or EM ports really