"spi sucks fit a carb"

[Aragorn]

well further to my spi tuning guide a wrote i finally managed to get me bro's car on a rolling road with the mods done in the guide (gte cam, decat, GTE exhuast manifold and downpipe, ashley GTE system)

car made 64bhp at 6200rpm (rev limiter) and 62lb-ft of torque at 2500 and 4500rpm (with a slight dip in the middle), and was leaning out a bit at the top (13:1 upto 4500rpm then leaned off to 14.5:1 from 4500 to limiter)

pity we cant increase the rev limit as the graph is a streight line right upto the limiter :(

it feels great to drive and that almost flat torque curve from 2500 to 4500 defo shows especially in lower gears and with it being stripped out with the buckets it keeps with a std SR reasonably well (and it ran an 18.8 quarter)

got some more mods up my sleeve but im trying not to move the power too far up the revs due to the limiter being so low, think im gonna try a mild cam, larger injector and possibly some headwork :)

[Nick]

sounds good, 64bhp isn't bad for a 1.2i

am i correct in thinking they are nearly 45bhp standard ?

[david dixon]

sounds good, how much was it before hand?

[Aragorn]

yup 45bhp at 5000rpm and 63lb-ft at 2800rpm

although i havent got more torque, my torque graph has a nice large plateau now rather than the small peak around 2800 that exists on the std engine

[david dixon]

well thats a good hike for mods that dont cost a lot! :D

[Nick]

excellent, so it really pulls more through the low end of the gears ?

[Aragorn]

pulls hard to the limiter in 1st and 2nd, doesnt really have the power to pull that well in 3rd and 4th (3rd is ok 4ths just shite lol)

could really benefit from a CR boxi think, its got std 4speed wide ratio box just now

as i said got some more mods up sleeve, gonna try n get rid of the leaning out at high rpms, perhaps push the ignition advance forward a bit and some other ideas i have swimming round in my head ;)

gonna be taking a trip to scrappy soon to size up some bits

i'll scan and post the bhp and torque graphs when i get the chance

[Adam]

well further to my spi tuning guide a wrote i finally managed to get me bro's car on a rolling road with the mods done in the guide (gte cam, decat, GTE exhuast manifold and downpipe, ashley GTE system)

car made 64bhp at 6200rpm (rev limiter) and 62lb-ft of torque at 2500 and 4500rpm (with a slight dip in the middle), and was leaning out a bit at the top (13:1 upto 4500rpm then leaned off to 14.5:1 from 4500 to limiter)

pity we cant increase the rev limit as the graph is a streight line right upto the limiter :(

it feels great to drive and that almost flat torque curve from 2500 to 4500 defo shows especially in lower gears and with it being stripped out with the buckets it keeps with a std SR reasonably well (and it ran an 18.8 quarter)

got some more mods up my sleeve but im trying not to move the power too far up the revs due to the limiter being so low, think im gonna try a mild cam, larger injector and possibly some headwork :)

64bhp, that is quite a great increase for basically, mods of a higher spec nova(gte)
I wouldn't expect the increase to be that much, so it has suprised me a lot.

It at least gives 1200spi owners some hope :wink:

[Aragorn]

the rollers were maybe a bit optimistic but not that bad really

a totally bog std astra X20XEV run 142bhp which is 4 up on std

the nova ran 52bhp at the wheels

if we ignore the calculations for flypower and just assume 15% transmission losses that gives us 52*1.15 = 59.8bhp

so even 60bhp isnt too shabby for the mods

the gte cam does increase valve lift by about 40-50% tho

std 1.2i has about 4.2mm lift and GTE has 6.12mm lol

[Adam]

How it struggles to the limiter in 3rd and 4th sounds rather much like my 1400spi astra, basically struggles reach 5k rpm in 3rd. And i have no comment in 5th gear :roll: :roll:
I don't even bother with 4th/5th gear :roll: :lol:

[burgo]

i spose the real test will be finish doing ya mods do a power run then swop to a carb and see the difference

[Stuart]

umm going to 13:1 is running rich. as is 14.5:1.

lean is numbers lager than 14.7:1 (ie 18:1 etc)

good results though

[Jack]

Carbs suck


arf :P

[Aragorn]

yes but at WOT full load situations u want richness over lean

14.5 is very near detting according to the operator bloke, he said the 13:1 is just fine tho for an NA motor at full load

turbo would be down into 11 or 12:1 under same conditions

[Stuart]

on a "std" engine (which technically your bros 1.2 is, if you take into consideration the performance) then 14.5 is fine at WOT since your still processing the same ammount of air which still requires the same stoich 14.75:1 AFR. When you start getting into the realms of proper engines that rev to 8K etc then yes proper richness is spot on same with msot turbos.

[getlost29]

as i said got some more mods up sleeve, gonna try n get rid of the leaning out at high rpms, perhaps push the ignition advance forward a bit and some other ideas i have swimming round in my head ;)



just to let u know u cant change the ingnition timing on the spi sytems, its all controlled by the ecu. its an multec msts, microprocessor, conttrolled spark timing system

[Aragorn]

well the idea is u set the dizzy to 10degrees by the normal method and the ECU advances from that point when it wants

however if i set the ecu to 15degrees as a baseline then if the ecu tried to get 30degrees advance it would actually achieve 35 as it has no idea where the baseline is set to....

the dizzy can still be moved just like it can on a carb engine, just the advance is controlled electronically by reading the TPS and map sensor amongst others. it still has a baseline and this needs set mechanically just like u would on a carb engine

[TomWilly]

so you used a performance GTE exhaust(manifold back) from what year exactly?

[Adam]

so you used a performance GTE exhaust(manifold back) from what year exactly?
I think he used:-
SRI manifold for the lambda probe hole
GTE downpipe
Then from the GTE downpipe he used an Ashley exhaust system for a nova GTE. He used the GTE system as it doesn't have a cat.

Well i think thats correct anyway :wink:

[TomWilly]

ok? so ive got a K reg 1.2 spi, what exhaust would you reccommend?

:?

[Adam]

ok? so ive got a K reg 1.2 spi, what exhaust would you reccommend?

:?

Ok mate, so you need your Cat for mot.
If you ain't bothered about the cat then fit a SRI manifold as you need the lambda probe hole.
Then fit a GTE downpipe and full GTE system.
You could either just fit a standard GTE exhaust system, or a performance system, like ashley etc.

If you need/want to keep the CAT then you could fit an SRI cat/system, and get a de-cat pipe for a SRI and re-fit the cat for MOT but have the SRI decat pipe on any other time.

[peester]

very good show - well chuffed. ought to be made a sticky or put in technical archives or summat.. 64bhp - thats more than std 1.4 spi makes (60bhp) and coming to within spitting distance of 1.3 sr's! (72bhp) remeber these 1.2 spi's are a insurance gr 3, mk2 only so - loads of low mileage, good condition ones about - strip one out a bit more - bet it wud suprise! quality.

[Aragorn]

my bros has no rear seats and cobra buckets and ran an 18.8 1/4 which imo is pretty darn good

the guide i wrote on tuning it is still stickied at the top under technical guides

i just need to update it with power figures

once ive tried these other mods ive got planned we might well have further improvements to shout about :)

[Cr4iG]

here some pics of the beast :) (im aragorns brother :P)

front
http://img.photobucket.com/albums/v...ob/P1010074.jpg
back
http://img.photobucket.com/albums/v...ob/P1010075.jpg

hopefully the next lot of mods should see us over the 70bhp mark. maybe even 75 :D if we get everything on the list :)

craig

[burgo]

kent view them

[Cr4iG]

gah, rob must have unhosted them :(

[Cr4iG]

front
http://img123.echo.cx/img123/4457/p10100749jx.jpg
back
http://img123.echo.cx/img123/8576/p10100753nm.jpg

those should work.

[burgo]

very nice indeed

[Aragorn]

it'll be at PV for folk to see, just need to persuade the little shite to put it on the NL stand instead of mig stand lol

[Rick_Nova]

been reading this, very nice job mate, what speed ya gettin out of it ? i got 1.2 k reg.. what did it cost ya too do all this? sounds good, when ive sorted other stuff out probs give it a go sommit similar!
cheers

[Cr4iG]

i had 125indicated, but it was about 100actual. its hardly cost me anything tbh. aragorn had the manifold and downpipe from his 1400engine, got the cam off brucey cause he upgraded, the ashley system was 130quid all in, cone filter and some gutterpipe came to about 30quid.

the engine was cheap, its everything else that was expensive: coilovers, wheels/tyres, seats, steering wheel, mk1 bumpers/skirts, paint, filler :S

[Rick_Nova]

oh right kool kool, soo ya rekon if i can get hold of a ... gsi downpipe n manifold? im guess 4-1 ? i got a powerflow system on atm? so i think i'll keep that lol, then a 1600 gte cam? if i got a 1600 gte cam, would i need 2 change anythin such as dizzy, or anythin like that?
cheers

[Cr4iG]

nope cam fits straight in, no mods. im using an SRi manifold because the 1.2i needs a lamda sensor, i know GTEs dont have one, and im sure GSis dont either. so ya need to get hold of an SRi manifold, unless some1 can say GSi ones have a lamda

[Rick_Nova]

oh right cheers mate! i bin offerd one for 15's so might be worth getting? erm i was kinda confused on the lamda sensor stuff? i dont mind takin cat out and then puttin back in b4 MOT, as its not for another year lol, if thats got anythin to do with it? lol

[burgo]

actually the best standard cam to get is one from a 1.4nv engine

[Aragorn]

your powerflow system wont fit a GTE downpipe, but a power flow dealer should be able to modify the system to fit the downpipe easily enough


if you goto technical guides sticky at the top of the technical forum and look at my 1.2i tuning guide

ive wrote a essay lol on everything ive done to this engine pretty much

i'll update it once ive tried the new things out and report back

[Rick_Nova]

oh right lol im pretty clueless at this stuff atm! ive read up on it! very nice mate, will any downpipe fit on to the powerflow? if not i'll try a powerflow dealer, will the sri manifold fit?

[Adam]

nope cam fits straight in, no mods. im using an SRi manifold because the 1.2i needs a lamda sensor, i know GTEs dont have one, and im sure GSis dont either. so ya need to get hold of an SRi manifold, unless some1 can say GSi ones have a lamda
IIRC GSI have a lamda probe hole.

Car looks well tidy mate.
Love the mk1 styling and the wheels :wink:
and at least its got a bit more go than the standard 1.2i. :D

[getlost29]

well the idea is u set the dizzy to 10degrees by the normal method and the ECU advances from that point when it wants

however if i set the ecu to 15degrees as a baseline then if the ecu tried to get 30degrees advance it would actually achieve 35 as it has no idea where the baseline is set to....

the dizzy can still be moved just like it can on a carb engine, just the advance is controlled electronically by reading the TPS and map sensor amongst others. it still has a baseline and this needs set mechanically just like u would on a carb engine

ok i think i understand, so where u have got ur refrence point from factory, where u set the arrow on the dizzy to the senter of the rotor arm at tdc for cyl1, u would move the that arow back or forth along as it is still pointing on to either side of the rotor arm.


i did try advancing mine a will ago but didnt run so well so i just set it back and left it

[Aragorn]

then u prolly either went to far and had it pinking or went the wrong direction and ended up retarding it

[Ste L]

nope cam fits straight in, no mods. im using an SRi manifold because the 1.2i needs a lamda sensor, i know GTEs dont have one, and im sure GSis dont either. so ya need to get hold of an SRi manifold, unless some1 can say GSi ones have a lamda
IIRC GSI have a lamda probe hole.


i think its just the late gsi's that have go that C16SE engine

[burgo]

put any exhaust on you want and make a lamda sensor hole

[Aragorn]

yer that is true but unless its very close to the original position then you'll need to get a heated sensor

[burgo]

yer that is true but unless its very close to the original position then you'll need to get a heated sensorwhich is still easy enough to do lol

[Adam]

yer that is true but unless its very close to the original position then you'll need to get a heated sensorwhich is still easy enough to do lol
I would just rather fit a manifold with the hole already there, saves the hassel. lol :lol:

[burgo]

yer that is true but unless its very close to the original position then you'll need to get a heated sensorwhich is still easy enough to do lol
I would just rather fit a manifold with the hole already there, saves the hassel. lol :lol:only take a drill and a welder ya lazy get

[Adam]

yer that is true but unless its very close to the original position then you'll need to get a heated sensorwhich is still easy enough to do lol
I would just rather fit a manifold with the hole already there, saves the hassel. lol :lol:only take a drill and a welder ya lazy get
Yeah true.
But a screwdriver is about the limit of my capabilities :wink: :lol:
If you knew what you were doing then i spose it would be easy to do :wink:

[getlost29]

then u prolly either went to far and had it pinking or went the wrong direction and ended up retarding it

where did u get ur information on changing the igntion timing on the spi then. cause when i looked it up in the autodata book in uni it said u were unable to change the timing.

if u got a web page or book refrence would be handy cheers

[Dave]

would be interesting to see what a 1.2 carbed model with 1.6 cam, uprated carb possibly (webber 32/34 twin choke) and ashley exhaust (basically the same sort of mods but done to a carbed) would put out

[Adam]

would be interesting to see what a 1.2 carbed model with 1.6 cam, uprated carb possibly (webber 32/34 twin choke) and ashley exhaust (basically the same sort of mods but done to a carbed) would put out
it would probably make more than this 1.2spi does. But thats with changing the carb and inlet. So thats more mods than done to the spi :wink:

i doubt tho that a 1.2carb engine would make about 20bhp with a decent exhaust and 1.6 cam.

i think basically it is not the actual SPI system that gives it low power, its the other things, like the crap cam, the cat, and the crap head. If everything was the same on both 1.2carb and 1.2spi i wouldn't doubt that the spi would make the same power if not more than the 1.2 carb :wink:

[Dave]

it would probably make more than this 1.2spi does. But thats with changing the carb and inlet. So thats more mods than done to the spi :wink:
thought he said he changed injector?
i assume the bottom ends are the same so what are the differences between the carbed and injected heads?? ports / valve size / cam??

[Cr4iG]

i aint changed the injector, yet.

the Carb head has bigger ports(cathidral type) the Spi only has tiny square ports, like the 1.4SR head

[Adam]

it would probably make more than this 1.2spi does. But thats with changing the carb and inlet. So thats more mods than done to the spi :wink:
thought he said he changed injector?
i assume the bottom ends are the same so what are the differences between the carbed and injected heads?? ports / valve size / cam??
IIRC he hasn't changed anything on the inlet side of things, as Craig said.
Its the nice 1.2carb head that gives it its extra bhp :wink:

It would be interesting to see what bhp is like with the identical head/cam etc, then just carb inlet Vs spi inlet.

[Aragorn]

im gonna look at mating the tbi unit to a carb inlet manifold could be a little tricky tho (it will become obvious once i get some pics of a carb inlet)

then that will allow me to fit a carb head

some other ideas first tho, i wanna have a play with the timing ;)

[m.d.]

fit the spi inlet to a carb head and port match the manifold. (may need to add material first by tig welding it then re porting to get the shape)

not sure if the 1.6 SPI injected single point throttle body (basically the carb looking thing lol) is any bigger. that may be worth looking at too

[Aragorn]

spend today pillaging scrapyard for some parts

u cant port match SPI manifold to carb head as the ports are outside the boundaries of the spi ports (if u bolt an Spi manifold to a carb head u can still fit your finger in the ports lol)

so i'm gonna look at making an adaptor plate up similar to the 32/34 adaptors and see what can be done with carb manifold

got some new bits to fit today, i'll try n get some pics and feedback once we get round to fitting them, got some porting to do and only got a file :(

[m.d.]

mate i got myself a cheapo drill for a tenner and just baught a few carbide burrs and a sanding flapper wheel. not as accurate as a die grinder but still good.

[Aragorn]

where uget carbide burrs from?

think homebase will have em?

i think i'll go have a look there today and if i cant get them then i'll goto hardware shop on monday

i assume i can use sanding flapwheel on the inlet manifold throats too? as long as i stick to ~80grit? as the std finish is VERY rough lol so would be nice to smooth out as much as possible when its off

[m.d.]

yeah 80 grit is fine and you only have to worry on the inlets when it gets shiny. you need to polish it to do that anyway

[Aragorn]

well today we fitted some more things to the engine :)

1.8 cav Throttlebody
1.6spi astra inlet manifold
1.4 spi injector

cav tb has 45mm butterfly compared to the 1.2's 35mm butterfly so thats a 60% increase in throttle area

the 1.6 inlet has a 38mm butterfly plus has something that resembles a weber choke in the manifold which when removed gives a 43mm hole so only a little bit of porting to make it line up, and unline the 1.8 item it fits the smallblock

1.4 injector was just added to see what would happen and seems to be fine :)

and here some pics:

the 1.2 manifold on the car:
http://img64.echo.cx/img64/8329/manifoldbefore9ds.jpg
both manifolds and Throttle bodies together for comparison:
http://img48.echo.cx/img48/2271/comparison8kc.jpg
the new setup on the car:
http://img125.echo.cx/img125/9569/manifoldafter0nz.jpg

craigs verdict is its defo imporved performance somewhat so we need to get it on a rolling road to see what kinda difference its made

im gonna have a play with the timing tomorrow or wednesday and see if we cant wring some more ponies out of it on super unleaded fuel

[Adam]

Looking good.
Does that astra 1600inlet mate straight up with the 1200head?
And does the cav TB just have the same sensors as the 1200, the TPS etc all work fine on the 1200 ECU?

Be interesting if something similar could be done on the 1400spi astra engine.

[Aragorn]

yep all this can be applied to astra engine as the 1400 shares nearly all its parts with the 1200

the 1600spi inlet mates streight upto the head with no problems

ive got a 1400spi im rebuilding for my GF's astra and a few of these mods will be being applied to that also, i wont be decatting it to start with as its an L-Plate and needs and MOT but ive got an SR cam and im gonna get the 1.8tb and 1.6inlet for that too

after that a 1.6mpi manifold and downpipe, decat bypass thingy and perhaps a aftermarket exhaust system

[getlost29]

have u tryd to see if any of the spi manifolds will line up with the 1.2 carbed head, or have u though about using the sri head and 1.6 or 1.8 spi manifolds if they line up

[Aragorn]

i have

spi manifolds are miles away from both the carbed and mpi heads ports are higher and off to one side

with the spi manifold bolted to a carb head u'd prolly be able to put your finger in the port :p

im gonna look at making an adaptor flange for a carb manifold and maybe even mod it to fit a mpi head although that involves adding metal to the carb manifold i recon the bigger valves on the mpi heads will help things

the other option is a 1.6spi head, it has the same 38mm inlet and 31mm exhuast valves as the mpi heads but obviously has the square ports, i dunno wether the larger valves and sqare ports will be better than the 1.2 valves and better ports

anyone know which causes more of a restriction?

[Adam]

yep all this can be applied to astra engine as the 1400 shares nearly all its parts with the 1200

the 1600spi inlet mates streight upto the head with no problems

ive got a 1400spi im rebuilding for my GF's astra and a few of these mods will be being applied to that also, i wont be decatting it to start with as its an L-Plate and needs and MOT but ive got an SR cam and im gonna get the 1.8tb and 1.6inlet for that too

after that a 1.6mpi manifold and downpipe, decat bypass thingy and perhaps a aftermarket exhaust system
Be interesting to see what improvements there is then.
Does the Sr cam fit into the cam carrier, as its got the extra lobe for the mechanical fuel pump.

If i keep mine long enough, and there is a performance improvement, may try them mods on my 1400spi, its on a Jplate, so Cat and MOT is no problem for mine.
The thing letting down the 1400spi is the shit cam, and crap head, just like the 1200spi.

Does the 1.6mpi manifold/downpipe have a larger bore size than the 1400spi one?

[Aragorn]

its a 4-2-1 design like the nova sr instead of the 4-1 u have now so should flow a bit better

the nova 1.4sr made 72hp and the 1400spi made 60hp, with the sr cam and no cat u should be approaching the 72hp again

as for the head, 1.3 and 1.4 sr only had 2hp between them

the 100cc capacity increase should have given a 6hp increase so that shows the restrictiveness

[Adam]

its a 4-2-1 design like the nova sr instead of the 4-1 u have now so should flow a bit better

the nova 1.4sr made 72hp and the 1400spi made 60hp, with the sr cam and no cat u should be approaching the 72hp again

as for the head, 1.3 and 1.4 sr only had 2hp between them

the 100cc capacity increase should have given a 6hp increase so that shows the restrictiveness
Ahhh.
So the Sr cam fits fine inside the spi cam carrier?

[Aragorn]

yup mines installed in a nova GTE carrier but they are identical to the spi one

[Adam]

yup mines installed in a nova GTE carrier but they are identical to the spi one
Cool.
Looks like i am heading to a scrappy then. :)

:+: