Injectors for a 2.8 stroker

[Mikey_Boy]

Hello folks,
Me again.. The 2.8 saga continues! Managed to get a 288 cam and some uprated rockers and valve springs. Next port of call is injectors - I have heard conflicting messages about injectors and what you should or should not do.. The spec I have in mind for the engine is as follows:

2.8 stroker (M52 crank, 130mm rods, custom pistons, 12:1 CR)
288 cam
MAF conversion
BTB exhaust
BB Throttle body...

I also have a WAR chip in mind as well so bespoke maps aren't a problem. With the wind behind me I am hoping for about 220hp so thinking that the standard injectors might struggle.

Any pearls of wisdom out there to help please? M30 injectors? M52??

Many thanks all!
Cheers,
Mikey_Boy

[Ant]

M30 inj, good choice, will be defo required with a MAF and capacity hike.

[HairyScreech]

do post how you get on with the 12:1 compression would be useful to know.

[Mikey_Boy]

Thanks guys for the advice! I am following Ant's wisdom on the 12:1 compression direction... It makes good sense so just need a brave pill to follow up it!

Cheers,
Mike

[Ant]

12:1 static is not that high, built em higher than that without issue

[Mikey_Boy]

Thanks Ant! Your advice is gold dust....

By the way - Would these injectors do the trick:

Part number 0280 150 714

Yellows from a 3.0 7 series auto??
Cheers,
Mike

[Ant]

714's are perfect, get em properly cleaned and flowed before fitting though !

[HairyScreech]

interesting, i was working to an 11:1 limit.

what fuel were you running them at 12:1 on? 98ron?

as id prefer to keep mine 95ron safe.

also curious as to what pistons you were using for that ant, and what the shape of the combustion chamber was, as thats the critical factor.

that one iv shaved down is 12.5:1 without valve cut outs, and i assumed automatically that would be to high for a road engine (just from experience with other engines) i would expect it to be around 11.5-12:1 once cut outs are added.

im also looking at making some piston guided rod set ups as soon as i get some time. (back at uni now.)

[DmcL]

what about some E36 323i/325i injectors? they flow 18.1lb tho its at 3.5 bar but they do have an advantage.. they are 4 pintle injectors. ive got a set in my M20 at the minute tho i havent got as much done to mine so im only running them at 3 bar which is about 16lb. even at 16lb the butt dyno thinks they feel generally smoother and with no apparent drop in power compared to the 19lb single pintle (M30 incidentally) that i was using before that (including relevant tuning to fuel/injector related maps, wasnt comparing running rich on 19's to running normal-ish on 16's before anyone thinks it).

u could get some E36 328i or even maybe M3 injectors but i say 323i/325i as they seem to come up for sale alot more often. ive had 3 sets of them so far, sold 1 set with a chip tuned for them, have another set im doing the same with and then the 3rd set are in my car at the minute. also 2 sets of 19lb injectors as well, one set of lucas and one set of bosch 714's and if u want to split hairs ove also got 6 lucas D3762FA's but 2 need the wee 3 hole spray diffuser and new filter baskets so im not counting those

the part number on those 323i/325i injectors are 0280150415 if u want to check them out. i have a walbro 255lph pump in mine now but on a standard replacement VDO pump before the walbro went in i didnt have any issues running 19lb injectors or an adjustable regulator running additional fuel pressure so pushing 3.5 bar on the 415's shouldnt be a problem even on a standard pump.

[e301988325i]

m30 injectors are 4 hole types if I'm not mistaken?

[phelix]

What pistons are you using?

[Mikey_Boy]

Plan to use custom pistons - probably from Ireland Engineering or similar...?

Now I have a build sheet in mind (see thread here):

http://www.e30zone.net/modules.php?name ... c&t=185881

I am now deliberating what ECU to use - currently I have a Bosch 1.3 with MAF conversion courtesy of Miller, but considering Megasquirt to get rid of the MAF and go MAP with wasted spark..

Also still chasing an extruded honed intake manifold as well...

Cheers,
Mike

[AlpineAde]

Ireland Engineering do them (intake manifolds), as do these guys:

http://www.vintagebmwsource.com/e30-intake-exhaust

[GeoffBob]

12:1 static is not that high, built em higher than that without issue

I am inclined to agree since actual combustion pressure and temperature (governing the onset of detonation) is a function of the residual mass fraction of exhaust gas in the intake air. While a higher CR is easily shown to reduce the residual mass fraction (further promoting detonation above that purely due to the higher CR itself) the mass fraction will remain high due to the large valve overlap provided by the proposed 288' CAMS. I would thus suspect that if detonation were to rear its ugly head it would be while the engine is "on cam" and not before.

I personally would hesitate to raise the CR of an engine to 12:1 on pump fuel using conservative (stock) cams, but that may well only be an indictment of the local fuel quality. However, given the opportunity and finances I still wouldn't mind giving it a go.

[Mikey_Boy]

Thanks Geoff - all very good points...!

Local fuel quality here in the UK is pretty good if you stick with the big brands so hoping that we should be fine there - Shell V Power in the UK for example is rated at 99-101 Octane even though the premium spec states 97RON here. And from what I know BP premium grade also exceeds the specification. Even the base 95 grades are pretty good to be honest - supply and distribution of fuels here works well.

Drawing from (very old and wise!) experience - my dad used to use 12.5:1 on his rally Mini engines in the 60's with no issues - again, the large overlap on the (quite basic) cams employed helped there a lot even if the ignition control didn't!!

Now all I need to do is get the cash together to get started, but notice still that Jhonno's S50 is still for sale... But that's the easy way out!

Decisions decisions!
Cheers,
Mike

[goosiegander]

I'd honestly recommend the s50 if you are chasing power,

If not and you quite like the m20 (like me) then the above looks like a very nice spec

[Mikey_Boy]

That's the trouble!! Loing my M20 boat anchor....!

The power of the S50 doesn't bother me - doing a conversion is a different challenge to massaging an engine.

All said and done, I think I am too far down the M20 path to turn back now!

From your thread goosiegander - seems your 2.8 is going well??

[phelix]

I would offer that if you're going with custom pistons why not go with an 89.6mm crank to maximise the potential that custom pistons can provide?

[Mikey_Boy]

I did think about going with the longer stroke crank having seen various threads around larger engine... However, when a 2.8 crank from an M52 came up at the right money I couldn't really turn it down!



Cheers,
Mike

[DmcL]

not add a windage tray and/or crank scraper onto the list? sounds like the engine/car are going to be made to see some tours of duty at the odd trackday and whatnot.

i just picked up a scraper for my 2.5, looks like a nice peice of kit but lord only knows when ill get around to fitting it.. engines in car and running sweet as a nut atm and im not sure if it would be do-able just by lifting the engine a bit in the engine bay or not.. sump and oil pick up pipe have to come off for fitting so might be an out of the car job

[Mikey_Boy]

Ah yes! I have seen windage trays on Ireland Engineering's website - they look great for the money.. Not sure of I mentioned it before but a baffled sump is sat in the garage ready to go as well...!

Sump off with the engine in the car is do-able but tricky...

I understand about your engine running sweet as a nut - what I love about M20s is that they love being thrashed!!

[Coyote_ar]

if you are going for custom pistons, why are you using the 130mm rods?

im going for a 2.8 build myself (boosted), but i will be using some 135mm eagle rods, to try to keep a nice rod/stroke ratio.

Cheers.

[Mikey_Boy]

Good point - reading other threads on this forum, I am now going to use 135 rods for the reason you state...

Cheers,
Mike

[Coyote_ar]

plus i believe 135mm rods are lighter, specially if you go for the M52 ones if i recall.