POWER OUTPUT

[DAM1T]

Recently bought my 89 plate GT2 for track day use. Its been stripped out lowered etc and has a weber conversion.
Question is
What sort of power output did the original 1.8litre engine put out?
What power increase if any did the weber conversion give?
and what sort of power can I expect from a conversion to twin 40DCOE Webers,
Oh and at what point do I need to start worrying about the gearbox being up to the increased power

[ianaudia4]

GT2 = 90 BHP standard.

[Nate]

What power increase if any did the weber conversion give?

theoretically, it will reduce the power as it is a slightly smaller carb. in practice they can be set up by a semi-skilled chimp, but most decent mechanics can't set up a pierburg, so chances are it runs better
+

[thebrief_1979]

mine with a weber was 97.9 bhp on a rolling road - it has a jettex now - should have added a few horses

[MRMENDER]

No point in fitting twin 40's unless you improve the exhaust too

[DAM1T]

Thanks for your replies guys. Time to get her on the rollers and check where I'm starting from

[wassell]

if you're blowing 3-400 pounds on the twin 40's, id be tempted to save a little more and drop a valver engine in her too. difference between the 8v and 16v is huge, and theres a few problems with running twin 40's on the 8v.


you'll need a GTi head as the carbed head has a water outlet to heat the manifold. alternatively you can try and blank this outlet or find a dcoe manifold with the water flange covered.

secondly, the carbs are placed just over the exhaust manifold. which isnt ideal due to radiated heat from the exhaust meaning you'll be sucking in warmer air. however, i have seen someone turn their raintray into the airbox, which looked very good and will help.

if you want a track toy, the valver engine will give you more smiles for less work to the stock motor.

that said the 8v is more than enough fun for most. drop a GTi cam or something lairy in her and you'll have a great time.

[roccodave]

the standard box should be ok up to about 180 bhp that is what tsr allways used to recomend

i had a webber/exhaust and air filter and was at 107 bhp on the rollers

if you add 40s/manifold/port polish the head and fit a cam gona be strugling to get 150 bhp so as others have said best off gathering the reqired bits to fit a 16v

btw bike carbs are a realy good cheaper option to 40s cost is around £200 or even less if you have a mate who can make you a manifold they will produce around the same power and don't go out of tune every 5 mins

[wassell]

bike carbs are great....if you get a decent manifold.

if going that route, id 100% flat out say you phone bogg brothers and buy the carbs and manifold off them. 300ish quid but great value as they come roughly jetted too. my custom aluminium manifold has cost me 150 pounds, the previous manifold cost me 70 (which works, but had issues with size), and the carbs were 110 with lots of extras.

i'd have saved a good wack if i went to bogg brothers in the first place.

only problem is that 45's (dont go 40's on a valver if anything more than just a cam has been changed) with 38mm chokes are better for fuelling than the bike carbs. the bike carbs arent as accurate (which can be seen on a dyno) and you'll loose mpg over the weber. but they are a damn site cheaper.


if i was to do it all again though....id probably go for weber 45's with 38mm chokes. but only because im a tart