4AGE ITB's Rolling Road session

[byd1380]

I agree about the injectors, they wouldn't make any difference, we tried richening the mixture at the top end but it made no effect on power. I think the main problen is the engine is tired and very, very smokey at high revs. And also because the engine is in a MG midget the exhaust manifold is very restrictive, 4-2-1 all before it exits under the car, with tight 90 degree bends, this is the only way it can fit in the car. So I am happy enough, probably most impressive is mid range 4000-6000rpm. I use the car for autotesting so this suits me fine. I am going to an event on sat so will hopefully put some vids on youtube.

Ivan

[jos 4 age]

good luck on the event.

[parrot]

robokill Wrote:without any head work (porting or other cams) I don't see the gain in using itb.

I agree. Though like everyone else on here, this car will no doubt be a work in progress.

My point with injectors still stands. What does a 'Standard' injector refer to in this case? 182cc, 200cc, 210cc or 213cc? Perhaps a smallport 250cc? There is a lot of potential variation there.

Presumably these runs were done on a chassis dyno. Toyota got close to 200ps on an engine dyno using 250cc injectors on a group A 16 valve. Meanwhile a standard 20 valve uses 295cc injectors. In this situation the air displacement is greatly increased with the 4 throttles compared to a single throttle plenum. Presumably fuel demand also increases in a linear fashion.

Allowing for transmission losses, I doubt a 182cc injector would cut it in this situation. If you utilise the approximation of HP = cc per minute /5, a 182cc injector will only produce in the vicinity of 145hp at the flywheel.

What colour are the injectors?

But once again,

robokill Wrote:without any head work (porting or other cams) I don't see the gain in using itb.

[ghostgrunt]

Parrot,

No offense,but if you'll look at Ivan's dyno sheet,you'll see he has more than enough fuel flow to support his power output.His A/F ratio trace is rock steady,and between approximately 13:1 and 12:1 as rpm increase.If anything,he might even want to lean it out a bit!Any richer and he would most likely begin to lose power.As was mentioned earlier,higher-flowing injectors are only needed if airflow into the engine warrants it(via porting and more aggresive cams,like the GrpA engine you mentioned above).