1800 tb 1600 manifold 1.2 spi

[johnny27]

Had a suggestion on a thread of mine a while ago. Got my corsa 1.2spi engine built up again with the 285 cam. BTW its made more difference to power than a thought it would, considering i'm using the spi cyclinder head. Anyhow tomorrow i'm picking up a cav 1800spi throttle body and a astra 1600 inlet manifold, a couple of questions please.

When porting out the top of the 1600 manifold, can i use a demerl (sp?) tool with the little cutting/polishing stone? Is there much metal needed to be removed to clear the flap in the 1800 tb?

What sorta effect can i expect, will it help the power any, or does it just help the throttle response like a perfromance airfilter does?

If any can make a estimate of a bhp figure, here's the pathetic spec so far: 285 cam, foam filter, decat, straight thru exhaust system and this new intake mods?

I'm hoping to pick up a 4 branch for the corsa also, so hopefully with all these mods i could see 68hp or so, no rocket ship but alot better for driving.

[Adam]

IIRC
You need file down about 2-3mm of the inlet.
Use whatever you want to do it with, the inlet should be left quite rough, not smooth.

Whats the SPI engine drive like with the 285 cam? Nice?

[garyc]

I think you need proper cutters for aluminium, stones tend to block up then generate lots of heat. You will be there for ages with a Dremel they are too small!

[johnny27]

got the tb and manifold today, just need to blank off the egr valve. Is the TB a straight swap as regards wiring, pipes?
Corsa with 285 cam runs fine, almost normal at idle, and reckon its added maybe 4-5bhp. Runs alot better than i thought it would.

[Adam]

I didn't think SPI engines had a EGR valve?

Ye, TB is a straight swap, unplug old and plug in the new.

[johnny27]

my new 1600 astra manifold has a egr port, is it just a simple as blocking if off on the top of the manifold? And will i need to block off the extra hole where it enters the head? as my 1.2spi head has no hole for the extra port
Any idea of what power gains i can get

[Adam]

Not sure on power gains, maybe a few extra bhp, as a larger throttle body allows more air in=more fuel=more power.

Could you not find a 1600spi engine without a egr valve, im not sure how your going to block it off.

[johnny27]

I've been told to just make a small metal plate for it, and bolt it down on the threads and use some silicone.

[craig green]

If theres no hole in the head then the hole in the manifold wont cause any issues. do as you said seal irt with silicone, unless it has an opening from one of the ports to thin air.
I'm basing my guess on EGR from Nova GSi. When I blanked mine off I just made a plate & used a new gasket.

[johnny27]

Fitted all today, car won't start is flooding and petrol pissing out of the housing on top of the spi unit? I made sure to change the injector to the 1.2 one. Only thing i can think of that is different is the vacum hoses at the bottom of the carb can any help? cheers

[Adam]

Petrol is leaking from where??
The airbox on top of the throttle body?

[johnny27]

found the main prob, injector not properly seated. Car's not idle'ing properly now think its timing problems

[Adam]

Is it idling too high?

You have to adjust the throttle stop to get it idling correctly.

You might also be better with a 1.4 injector in, might cope better with the extra air going in.

[johnny27]

yeah its idling very high, altought throttle is fully closed so the stop is alright. Could an air leak cause high idling?

[Adam]

Ye.
Check the pipes to the MAP sensor, they can cause an air leak.
Also check that all vac pipes are connected on the throttle body.

I remember when Aragorn fitted the 1.8tb he had to adjust the throttle stop, as it was idling too high.