VauxSport - Vauxhall advice and chat forum

bluecorsa20se · Posted: Mon Sep 28, 2009 7:08 pm Post subject: spi throttle bodies

hi, anyone know if the spi throttle bodies on smallblocks have different injectors fitted based on engine size? I.E a 1.2 body will have a smaller flowing injector than a 1.6 spi body? or maybe have different butterfly sizes? or are they all the same and the ecu controls opening time to suit engine size? im only asking because im swapping the dead 1.2 out my nova to a 1.6 astra spi engine but it didnt come with a throttle body but did come with ecu. cheers.

AL · Posted: Mon Sep 28, 2009 9:30 pm Post subject:

iirc all the spi engines have different throttle bodies entirely - some fit others but I doubt a 1.2 TB will fit a 1.6 inlet tbh, let alone run very well...

Plenty available in scrapyards!

bluecorsa20se · Posted: Mon Sep 28, 2009 10:47 pm Post subject:

the 1.2 tb does mount up to the inlet properly and the plugs for the tps and icv are all the same,i tried it a few minutes ago with the 1.6 ecu after eventually getting past the immobiliser circuit and it starts up but i will get a 1.6 tb tommorrow to make sure because i agree it probably will be set up to suit the characteristics of a 1.2 because it sounded flat and underfueled on WOT but idles ok. cheers for the help.

alistairolsen · Posted: Mon Sep 28, 2009 11:10 pm Post subject:

the injectors are all different sizes.

The TB on a 1.2 and 1.4 were the same at 32 or 34mm, not sure about the 1.6 but the 1.8 is much bigger at 45mm.

I used to run an 1800TB with a 1400 injector on a tuned 1400 engine making about 90bhp.

topspray · vauxsport.com Joined: 01 Oct 2009 Posts: 8

injector
part number 4850 is the 1400
part number 5278 is the 1600
part number 5277 is the 1800
throttle body 1400 is 35 mm
throttle body 1600 is 38 mm
throttle body 1800 is 44 mm

if using a bigger throttle body then the inlet manifold where the throttle body bolts to needs porting also tb tops are all the same on the spi from 1200 to 1800

throttle valve
part number 80699 is the 1400
part number 80700 is the 1600
part number 80668 is the 1800

topspray · vauxsport.com Joined: 01 Oct 2009 Posts: 8

Long Live The Nova · Posted: Sat Feb 27, 2010 10:54 am Post subject:

Yes they are the same fitment, but have different sized throttles.
1.2 and 1.4 had the same tb, but 1.4 had a bigger injector.
1.6 tb is bigger, and 1.8 tb is bigger than the 1.6 one.

But obviously just shoving a 1.8 tb on a 1.2 manifold wont work too well at all, because there will be a 15mm "step" where the inlet port is smaller than the throttle.

topspray · vauxsport.com Joined: 01 Oct 2009 Posts: 8

Long Live The Nova · Posted: Wed Mar 03, 2010 11:50 pm Post subject:

Plenty of bigger 1.6 inlets in scrappys. Miles easier option than spending ages taking 10mm off the 1.2 inlet. Plus the 1.6 inlet is larger all the way down the intake, if you get me, it doesnt taper

topspray · vauxsport.com Joined: 01 Oct 2009 Posts: 8