E30 Zone

I keep reading about larger bore throttle bodies. Now I agree that a larger one should help with air flow. But in my previous experience of fitting a larger they don't really make that much difference on their own, but they help. I've seen some rather ludicrous claims for larger throttle bodies on these pages. So has anyone ever bothered to do a rolling road back to back test comparing a std throttle and a larger one?

Same with the various chip options talked about. On Vauxhall engines we found that so called performance chips generally did nothing at all, or gained 1 or 2 BHP somewhere and lost a few somewhere else. ie: a total waste of time apart from a higher rev limit.

However, I understand that quite a lot of the BMW mapping is a bit restricted.

Anyhow, has anyone back to back tested a chip. If the answer is no then I might go and do a rolling road test myself with the best regarded chip for the 318iS.

On the Vauxhall side of things, the chips don't tend to do much as Vauxhall always rate their engines low.

For example, my stock 75hp rated 1.2 Corsa dynoed to 80.3hp on a RR that's considered to read slightly low.

i have a book here for tuning the a-series engine in the mini.

evey mod you can think of is dynod and charts to show the diefference on the stock engine.

also shows how adding on different things together makes a massive difference.

they also have a nice MPG chart after all the mods that shows the price you pay ! !

I dynoed a 318iS with the BBTB & Viper 2 chip. Print out said 146bhp @ the fly wheel. Don't know what it was at the back wheels. Will try to find the print outs...

I seem to remember the torque being up to 135ish... need to find the sheets!

Should have given more power but the car had a 'flat' spot for about 1000rpm where the power just levelled out, before dropping off again.

Car also had a KN panel filter, brand new BMW spark plugs, fully synthetic oil etc etc

Synthetic oil is a nono on your engine.

tourerti wrote:Synthetic oil is a nono on your engine.

why? it's what was recommended by 'the oilman' @ OPIE oils...

I use Silkolene Pro S 5w-40.

The car seems to run well, and sounds quiet...

I have always been of the understanding that a semi synth is best for the older bmw engine.

Im about to but some oil off Oil man.

I emailed him saying, "on an older engine would it be better to use semi-syn"?, and replied saying "fully-syn will be better for it".

So, im just gona get fully-syn.

I have heard this before but never off anyone other than oil man.

fully synth/semi synth its nothing to do with that its the quality and viscosity that is the important factors

E30Mark wrote:I dynoed a 318iS with the BBTB & Viper 2 chip. Print out said 146bhp @ the fly wheel. Don't know what it was at the back wheels. Will try to find the print outs...

I seem to remember the torque being up to 135ish... need to find the sheets!

Should have given more power but the car had a 'flat' spot for about 1000rpm where the power just levelled out, before dropping off again.

Car also had a KN panel filter, brand new BMW spark plugs, fully synthetic oil etc etc

I thought the 318is was supposed to have about 145-150hp in standard form? That would have been an estimated fly wheel figure though so it wouldn't be completely acurate (unless it was an engine dyno?). Did you have before and after figures? They would give the best idea.

Aston

They're rated at more like 135BHP.
Allowing for rolling road optimism (all coast down estimates are on the rosey side), let's say it made 5-10BHP more with the mods. That's a lot more than I'd ever expect really. I'm wondering if the ECU mapping was very restrictive. I don't normally buy into the benefits of chip swaps - I've never seen a decent gain on a Vauxhall engine witha chip (normally aspirated).

the M42 engines are heavily restriced in both air and fuel dude, we experimented with a BBTB and chips on the M42 and good some excellent gains through the rev range, yes there are some sacrifices in economy.

Due to the various parts used on the M42 however i dropped to zone M42 range as I didn't have the time to fully develop them for all the variances, these engines are very much a "parts bin " special

the BBTB for this engine leaves the part throttle small butterfly unmoded to keep velocity high, the main WOT butterfly is ported and enlarged however.

Talk to Ian with regard to the BBTB, and procure a viper and see whats what.

I think you'll be surprised with the results, these engines are tuned to run stoich through the rev range and I think we all know thats not good for power

14.7 AFR for economy 13:1 for power

Well I'll have to take your word for it, sounds quite encouraging that they restricted the engine somewhat. Has anyone ever tried throttle bodies or twin carbs on the engine? I'd be interested to hear what the head is capable of.

If it's running stochiometric then you could gain about another 5% out of it with about a 10% increase in consumption at WOT, just be richening. What was the spark advance like?

If I can locate a chip then I might go to the rolling road for a before and after session. However, I'm probably just going to leave the engine alone because I'm quite happy with it how it is and I've been down the tuning route before.

the advance curves are OK to be honest, you'd need to tweak to match the revised fuelling but not revoloution, evoloution.

If you're keen to have a tweak add a few degrees more advance to the intake cam( provision is there from factory ) to give the car more overlap, shows a nice midrange increase for the cost of the gaskets.

you can have stock +/- 3 degrees but no more !
valve to crown problems only an issue if you try more than 6 degrees.

The cam adjustment thing did appeal to me when I was reading about it a few days ago. When I took it all apart the ready made adjustment slots looked promising.
Is there anything to be had by retarding the exhaust cam a bit too?

Could be interesting, there are two variables to play with here and I've no idea what would give the best result. Would be interesting to try it on a rolling road and see what sort of outcomes are possible.

TBH I'm not really wanting more BHP, I like the car as it is; I OD'd on modding over the last few years. The slippery slope is always there though.....

go for it Tom.. i'd love to see what sort of gains can actually be had from the iS lump, many ppl talk figures but have nothing to back them up

i think they can actually be tuned to more than the XE from what i've heard but it is Ԛ£Ã”šÃ‚£Ãƒ”šÃ‚£Ãƒ”šÃ‚£

There used to be a throttle body faq on the site, where Bexleys did a before and after dyno plot on a 327 with a Bbtb. Does anyone have a link to it?

On this page, scroll down

http://www.e30zone.co.uk/modules.php?na ... techtb.htm

Adam

tomstick

also thinking of advancing my cam timing on my IS

heard its well cheap too, adjustable sprocket also so its obviously not a bodge mod so to speak

demlotcrew told me he advanced his by 5 degrees, had amazing mid to high range responde but devoloped a flat spot around 4000, iv heard that this is what happens when you install schrick cams also??

not to sure jsut my two cents guys

Good link this: http://www.e30zone.co.uk/modules.php?na ... techtb.htm

First up the power figure for the engine looks plausible, with it being 14.2 BHP/(litre 1000rpm).

They gained 2% power and 3% torque from a 17% area gain. That sounds fine too. Like for like that would take a 318is from 135 to 139BHP. ie: a 3-4BHP gain. That sounds plausible.

I think the cheapest method would be to fit a throttle from the 320/325 or whatever was suitably larger.

I did a similar thing to my 2.0 Vauxhall engine - I fitted a Carlton 2.5 throttle body and then "half mooned" the spindle. Word of warning though - the spindle broke 6 months later and luckily the bolts didn't get swallowed by the engine.

tomstickland wrote:
I think the cheapest method would be to fit a throttle from the 320/325 or whatever was suitably larger.

a 320/325 TB would not fit a 318iS at all......... completely different design

I haven't even looked yet and I wouldn't expect it to just bolt on. I had to have an adapter sandwich plate made last time. Not that I'm probably going to bother for a while anyway.

If you're keen to have a tweak add a few degrees more advance to the intake cam( provision is there from factory ) to give the car more overlap, shows a nice midrange increase for the cost of the gaskets.

About 5 years ago, when I'd first got my 325, I took it to a BM "specialist" to have the cambelt changed (thought it was wise...), and he looked at me very sternly afterwards and said "your cam timing was a tooth out".

I SWORE the car performed worse rather than better after that - the big rush at 4000 odd rpm was greatly reduced. So you mean he could have actually worsened the performance by correcting it???

(Goes looking for his shotgun...)

Yes, I've fitted a cam belt one tooth out before. Both ways actually at various times over the years. When it was one way the car had loads of low down torque but seemed a bit slow at high rpm. With it the other way round car had loads of go at high rpm but nothing a low rpm.