[Mk2] [Turbo] torque, why do rev1/2 produce more than rev3s?

[jimGTS]

general question, what is it about rev1/2 that produces more....

guess im only refering to stock turbos here, and ct20bs on rev1/2s...

[Hellboy]

map, camshafts, head design, inlet/exhaust outlet/manifolds and the ct26 is on before the CT20 and producing the goods lower down

[jimGTS]

map, camshafts, head design, inlet/exhaust outlet/manifolds and the ct26 is on before the CT20 and producing the goods lower down

but even on rev1/2s that have swapped to a ct20b you see high numbers....

i hope im not gona loose any by putting a rev3 inlet cam on...hopefully thatll just push the peak power up further (but no real hp gains)...

its not every rev3, but most are putting out 20+less than rev1/2s with basic bolt ons.

and i dont think its due to tvis really cause my figs are still quite high and ive disabled it.

just wondering what specific thing it could be really.

[mrfil13]

You got your headgasket sorted yet Jim?

Could it be anything to do with the higher compression of the rev1/2 engine? Just a stab in the dark really

[jimGTS]

na, still in the process....only got the odd hour here and there on weekends to do it, lol..
head should be off to nathan at century motorsport for a completely overhaul....
just gota clean up the block face on the weekend in prep for putting it back together.

[mrfil13]

I suppose it gives you an excuse to uprate a few internal parts to make it more reliable and maybe push more power.

[jimGTS]

I suppose it gives you an excuse to uprate a few internal parts to make it more reliable and maybe push more power.

exactly, its either take it to a garage, who'll do a standard hg swap in 2 weeks for say £500-800, or whatever it costs.
or i spend the time myself, know exactly whats happening, whats going on, knows what needs renewing, take time and care doing it, and fit a msl hg, arps, head overhaul, reshim, relap, rev3 inlet cam, skim, new valve stem seals, and numerous other headgasket gaskets/orings, plus get to clean it all up, spray it, remove bits i dont need, ie tvis butterflies, tvsv, tvis piping/parts all for the lower end of the quote above.
plus ill get to learn a crap load more about the car.

guess i just like an excuse to take the car apart....

[mrfil13]

If you have the time and can get away with no car for a while it will be fun also at the end of the day you will know the car is working because you did it which will put a grin on your face

While it's all out, if you havent done already maybe look at replacing the spring jubilee clips with some nice new screw ones, if they get unsettled they may start to leak, i found this when i had my engine swapped.

Good luck

[dawolf]

The rev 1/2 may have more torque but when you drive a rev 3 you can feel it is a fair bit quicker and the CT20 holds it's boost for longer. Admittedly rev 3's do 'kick in' a bit later. Mine is close to 4000rpm before it hits max boost.

[jimGTS]

The rev 1/2 may have more torque but when you drive a rev 3 you can feel it is a fair bit quicker and the CT20 holds it's boost for longer. Admittedly rev 3's do 'kick in' a bit later. Mine is close to 4000rpm before it hits max boost.

im not denying higher peak power over a ct26 (rev1/2), but torque on both a ct26, and when a ct20b is strapped to a rev1/2 is still more. (and on the latter, i dout theres much between the cars), hense my question....

im hitting 1.1bar (my set max boost) by 3k rpm on my ct20b dude....

[dawolf]

Yours spools a lot quicker than mine then. Maybe it's because you have a boost controller fitted with TVIS removed? Mine is standard.

[jimGTS]

Yours spools a lot quicker than mine then. Maybe it's because you have a boost controller fitted with TVIS removed? Mine is standard.

well you dont have a tvis, as you got a rev3
altho asuming you ment tvsv, this wouldnt effect spool. EDIT, altho saying that, perhaps the way the car brings in the tvsv (ie raising boost) , could be a tad slow

probably boost controller and downpipe then.
werthwhile upgrades dude.

[steve]

Yours spools a lot quicker than mine then. Maybe it's because you have a boost controller fitted with TVIS removed? Mine is standard.

stick an EBC on and you should get full boost by 2900-3000rpm.

i think with the ebc my old one was getting full boost by 2800-2900rpm.

the new one with an mbc gets full boost by about 3500rpm the same as my old one when it was standard.

rev1/2 with a ct20 nearly always make more torque, wouldnt mind finding out why?

[L0rdMike]

The rev 1/2 may have more torque but when you drive a rev 3 you can feel it is a fair bit quicker and the CT20 holds it's boost for longer. Admittedly rev 3's do 'kick in' a bit later. Mine is close to 4000rpm before it hits max boost.

im not denying higher peak power over a ct26 (rev1/2), but torque on both a ct26, and when a ct20b is strapped to a rev1/2 is still more. (and on the latter, i dout theres much between the cars), hense my question....

im hitting 1.1bar (my set max boost) by 3k rpm on my ct20b dude....

What sort of torque figure is yours making at 1.1bar?

[jimGTS]

well i made 278lb at 14psi, not mapped and on the rev3 ecu...
and 264 when i had the ct26 at 13psi couple of years ago.

at 1.1bar, no idea on my apexi fc map, 280-290possibly....

EDIT im not saying my car is any different to other rev1/2s, as ive seen many others with similar torque levels.

but having just looked at your profile and dyno results, i would be very wary of a place that gives you 90hp tranny losses! and expect your torque figure to be correct.

im not saying all btw, just majority.....

simply asking what is causing this.

[L0rdMike]

well i made 278lb at 14psi, not mapped and on the rev3 ecu...
and 264 when i had the ct26 at 13psi couple of years ago.

at 1.1bar, no idea on my apexi fc map, 280-290possibly....

EDIT im not saying my car is any different to other rev1/2s, as ive seen many others with similar torque levels.

but having just looked at your profile and dyno results, i would be very wary of a place that gives you 90hp tranny losses! and expect your torque figure to be correct.

im not saying all btw, just majority.....

simply asking what is causing this.

Powerstations rollers are odd, the wheel figures are wrong trust me.

Overall we thought the rollers fly figure was over by about 5%

A 172 Clio got 182 and other standard cars got about 5% more than they should of at the fly.

Also take my 2 rolling roads at 13psi and take 5% off of the Powerstation one and they are nearly the same.

[refo]

the inlet tract is different on the 1/2 cars and is a little more restrictive so the engine has to pull a little more to get the air in, this can aid the torque.

could be lots of things or a combination of lots of little things. compression ratio, boost control, inlet and manifold designs, head design, cams, map, air flow reading, cat design, exhaust, down pipe... or all of the above, maybe.

you could work it out on an engine dyno but it'd take a while. i'd suspect that the overall setup of the 3+ is more free flowing so the peek power is greater but the torque suffers as a result. at a guess that is.

[diycinema]

Yes, rev 1/2 have higher compression pistons. Aren't they 8.8:1 instead of 8.5:1? The intake must have something to do with it as well.

[mrfil13]

The N/A's are in the same situation, on those the exhaust manifold was changed on the rev3+ for less torque more bhp. Plus other stuff but that was the easiest.

[BenF]

My money would be on the higher compression compression ratio earlier cars had plus different cams.

The Rev3 cams breathe better at the top end but like NA cars you sacrifice a little bottom end, plus the lower compression will hurt torque figures slightly.