how to get more power

[michaelhare]

hi im jw if anyone no's how to get any more power out of my corsa b 1.4 8v many thanks

[c16se corsa]

few things really very easly tunable engine is it a multipoint injection or single?

[Robbo173]

Got any mods For the SPI 1.4 8v ?

[c16se corsa]

ive got all the stuff to turn it into multi point if your interested its a good starting point

[PRICER]

here you go mate, enjoy the read



GM 1400 8v Tuning


Basics:
The 1400 engine that is in the SR and all carbed 1400 (14NV) novas is the same, so in essence the 1400 sr is no faster than a 1400 hujimaflip edition. There are two injection 1400's, one is an SPI version and in all fairness a big pile of turd(14NZ), then there is the SRi (14se)... this is an excellent engine as its basically a 1600gsi lump but with a smaller capacity. It technically has the most potential out of all the 1400 8v engines but all of them have the ability to be great given the chance.

Head:
All 8v OHC small block GM engines have the same exhaust ports, which means that all 4 branch manifolds fit (further details regarding systems later) so there are no worries there.
The 1400 carb and Spi heads are pretty much identcle, they both share the same awful square shape inlet ports and similar inlet manifolds. The SRi engine has pretty much the same inlet ports and valve as the 1600 version. You might be lucky and find a 1400 sri head with no EGR hole, no worries if you do a simple tap of the hole and abolt fixes that, but dont forget thread lock (dan and jim know about this) if you go down the carbs route.

Anyway, onto getting more go from the engine.
If you want to take the 1400 sri head route or even putting a 1600mpi head on then first of all you need to measure the combustion chamber volume with both valves shut and a spark plug in, then with it on a flat surface and the bottom of the head pointing straight up, fill the chamber with a light oil (such as 3in1) from the syringe and keep track of how much fluid you put in there, when its level with the face of the head stop and thats the volume of the chamber.
Perform a similar test on the bottom end with a piston at TDC and record that value too. I belive the headgasket is 1.5mm once compressed down, but in most cases its ignoreable.
Opps forgot, this is all in CC (if your unsure how to convert what ever units you have done it in use a program called convert via google etc)
To calculate the Compression Ratio do the following:

Compression Ratio = (Head Volume + TDC Volume + Swept Volume) / (Head Volume + TDC Volume)

Swept Volume is the CC of the piston (eg 1/4 of the engines CC)

Basically you want to have a CR of about 11:1 so what you need to do is have the head skimmed a little to increase this. Also worth bearing in mind that if you have a rebore and fit bigger pistons then the CR will go up too, and also if the pistons are slightly higher compression than normal spec ones too.
id honestly say dont have much more than about half mm taken off the head as it alows for warpingin future ;o)

You can and should do this to any head/piston combo you want to run to work out your CR and make adjustments to the rest of the build accordingly.

The reason for using the 1400/1600mpi head is that the valves are bigger, and the ports flow better than a 1400carb/spi version. This in essence gives you the effect of a full porting/big valve job for the sake of about £30 on the skim... weve seen 8-12bhp gain from simply swapping to the mpi heads, which is what say a B+ head is advertised at doing.
If you dont want bigger valves then the next best head(s) are from the 1200 carb OR 1300 carb engines, just be wary of the CR increase as some can push it too far up

Its wise to have the top of the head checked for trueness to the bottom as its where the cam carrier sits and you can get uneven lift/duration from a wonky cam, also a light skim of the top of the head can effectively increase the duration/lift of a cam.... but its a little bit of a bodge in some respects, and increases the chances of binding the valve springs.

Youve picked your head, got the CR measured and adjsuted were nessecary marvelous.

Intake system:
With the Mpi heads you have lovely round ports and there are no single carb manifolds that fit/go with the ports so you can either run the injection inlet and run aftermarket engine management (megasquirt is a cheap home made option), Or the old skool way and fit T40's on a 1.6gte/gsi inlet manifold.
If youve gone for the 1.2/1.3 head route then you can easily fit a single carb such as a weber 32/34 direct replacement jobbie using the 1300 sr inlet manifold.

fuelling wise, you can run the std nova mechanical pump off the cam lobe BUT if your going for high revs id really advise against it as the pump could skip off the cam lobe and give iffy fuelling. So the answer is to fit say a facet red top pump at the back near the tank and then a regulator near the carb(s)

that was quick wasnt it ;o)

Cams:
Depending on how you want to use the car/how you want it to drive etc then the cam profile will basically determine this...
There are loads of cams available for the nova but there is little/no point getting one below a Kent AST2 in spec, this is about the minimum in terms of "point". Dan has had excellent results on his so they aren’t to be sniffed at but as said this is the minimum i recommend unless you’ve got rules saying you cant have it. There is also a Piper BP300 cam which is awesome and has shown good results in 1600's and a couple of 1400 engines, its a little less driveable low down than the AST2 but a good setup should clear most of that up, but it definately makes the engine want to breathe harder higher up the rev range(8K) where as the AST2 tends to run out of puff at 7K ish. There are lots of cams inbetween from Catcams, Newman, Enem etc its a matter of either talking to people who have a cam they like or seeing what specs others suggest based on experience. If you really feel daring you can go for a solid profile cam which puts you into the arear i like to call "silly". Ive fittd a semi custom grind of a Catcams Flat nose 306 degree cam to my 1200. but there are lots of other solid profile cams about, it just takes more setting up and a little more patience in the build to get them right but they take sitting at high rpms much better than the hydraulics do.

Bottom End:
Its fair to assume that any 1400 8v engine you have unless its been rebuilt lately is knackered...
At bare minimum its best to have the bores honed, new rings, deseam and shot peen the rods and fit ARP rod bolts with new big end/main bearings.
If you want a better spec then you will be looking at say a +1mm overbore and pistons to suit, maybe slightly higher compression versions (talk to your engine machine shop) and have the valve cut outs made a little deeper incase you want a "silly" cam. also its worth having the sharp edges removed from round the cutouts etc to remove potential hotspots that cause det.
Again de seam/shot peen the rods, ARP rod bolts, get the crank checked for wear and so on, new big end/main bearings. maybe have the rotating assembly balanced for high rev applications.
its worth renewing the oilpump too.
if you feel really frisky you can get the top of the block machined known as decking, to increase the CR without taking too much off the head, but you can work out the need for that with the CR calculation, but this worth making sure that the top of the block is flat for reliability.


General Bits:
Cam Pulley, if you dont want to pay the highish cost for a vernier pulley you can simply get the existing std pulley machined with a kidney slot around the hole that the locating pin for the camshaft goes (i paid about £20 for mine, compared to the £60+ that a "proper" one is)

When fitting the cambelt its worth trying to get the shorter earlier cambelt for your engine and disposing of the autotensioner and simply using the water pump since i dont trust the autotensioner (that is assuming you have one)

New water pump never goes a miss in a full rebuild.

Its wise to get the 1600mpi cam cover as its got a breater system on it and its also worth considering a 1600 cam carrier as that’s also got breather holes but this will mean you have to run an electric fuel pump. again its worth getting the 1600 breather pipe from the block to the cam carrier that then vents to the cam cover and you route a pipe to what ever kind of catch tank you want.

For gaskets in general try to make sure you get cork ones for the cam carrier and sump since these are generally regarded as better than the rubber ones that move all over the place.
And a good ole supply of RTV to make sure things seal ;o)

thats about it for the engine i suppose.....

[michaelhare]

few things really very easly tunable engine is it a multipoint injection or single?

not to sure how would i find out many thanks

[c16se corsa]

has it got a injector for each cylinder or has it 1 injector for all 4? easyest way to tell is by the inlet has it got a big one with the air intake and throttlebody to the left hand side or the throttle body in the middle with the big stupid black box with the 2 big pozi screws in it