The most Powerful 2.5

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M5pilot
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Post Tue Apr 19, 2005 11:23 am

Whats the most power an NA 2.5 has ever made? Im talking about bottom end standard but upgrades in terms of intake (TB's?) fuelling, head work + CAM + exhaust.

I'm pretty sure that rather than forking out Ԛ£3000 on a 2.7 conversion a 2.5 can be made very powerful for the same money.

Ive seen Dale's car make 196bhp with Dbilas TB's, 284/272 Cam, 6 branch + Scorpion and Stand Alone management. However his car only made 140odd bhp before that telling me his engine wasnt in the best condition to start with.

I wonder what the result would be if an engine made 170 bhp to start with then add TB's, Stand Alone Mangament, 284/272 cam, some good head work + 6 branch and exhaust. Ive heard 205bhp is attainable without TB's

I doubt TB's add alot more power to an engine in this state, they work alot better when the engine is alot "lairier" (higher compression, wilder cam, bla bla bla)

If Hartge can get 190bhp from their H26 kit which has no 6 branch then surely the above can make 200bhp+.

This way isnt cheap but its alot easier than say a 2.7 conversion where alot more time is required and alot more patience.

This is more about just getting the head work done, fitting the cam doesnt come into it because youd have to do that anyway if you wanted head work done, fitting a 6 branch and going to Dave Walker for Emerald Install. You could probably do this whole lot in 2 weeks.

A budget 2.7 conversion would be lucky to make 200bhp as it would wouldnt have any head work, no 6 branch and run on standard management.

There's no real reason as to why im writing this stuff, Im just really really bored at work! 8O
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Post Tue Apr 19, 2005 11:26 am

Tell you what, find out what you can do to a M42 if your that bored, cause im really not interested in the six pots. :eek:

Andrew
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Post Tue Apr 19, 2005 11:30 am

i was actually wondering the exact same thing the other day Sal started to write a post but then got bored! Tbh something around 220/230bhp must be obtainable with higer compression/headwork/lairy cam/decent exhaust/6branch n tb's with Emerald or similar
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Post Tue Apr 19, 2005 11:31 am

n when it was done the 2.5 would rev alot better due to bein more oversquare
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Post Tue Apr 19, 2005 11:35 am

Demlotcrew wrote:Tell you what, find out what you can do to a M42 if your that bored, cause im really not interested in the six pots. :eek:

Andrew
Hartge do a 160bhp conversion but its alot of money.

What about a MAF conversion? Makes a big difference on the 6 pots. Your only paying a few quid more than a remap and will defo give you better throttle response etc.
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Post Tue Apr 19, 2005 1:33 pm

i think MAF is a big problem for 4 pots... even worse for cold running issues.... ive heard this from Pete..he said one of his customers had a m40 tuned to the hilt.. then a MAF conversion also...(sad i know!) and pete said it was dangerous cos it was so poorly setup

maybe if it was setup ok it would work....

Karan
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Post Tue Apr 19, 2005 1:36 pm

isnt the cheapest ,most cost effective route route to a 200odd BHP E30 to fit a E34 535 lump?
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Post Tue Apr 19, 2005 1:37 pm

Cant the $pots use the e36 managment? The later e36 has MAF doesnt it?
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Post Tue Apr 19, 2005 1:40 pm

Karan wrote:i think MAF is a big problem for 4 pots... even worse for cold running issues.... ive heard this from Pete..he said one of his customers had a m40 tuned to the hilt.. then a MAF conversion also...(sad i know!) and pete said it was dangerous cos it was so poorly setup

maybe if it was setup ok it would work....

Karan
There's nothing sad about tuning an m40!!!! It's all about the love dude!!!

My car came with that enigne. It's gonna stay with that engine.

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Post Tue Apr 19, 2005 1:42 pm

Jhonno wrote:n when it was done the 2.5 would rev alot better due to bein more oversquare
Making an engine more over square won't make it rev any better, but if you had two engines of the same capacity and configuration, but one was oversquare and the other was under square, the oversquare would be more rev happy.

Unfortunately you can't really make an engine more hungry for revs without lightening the reciprocating parts and/or reducing the stroke.
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Post Tue Apr 19, 2005 1:44 pm

Makes sense, this is why the 2.7's which have lightweight Pistons, lightened cranks and rods rev just as well if not better than 2.5's.

Anyway, any known 200 bhp 2.5s?
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Post Tue Apr 19, 2005 1:47 pm

Turbo-Brown wrote:
Jhonno wrote:n when it was done the 2.5 would rev alot better due to bein more oversquare
Making an engine more over square won't make it rev any better, but if you had two engines of the same capacity and configuration, but one was oversquare and the other was under square, the oversquare would be more rev happy.

Unfortunately you can't really make an engine more hungry for revs without lightening the reciprocating parts and/or reducing the stroke.
thats what i meant i just didnt say properly.. i knew what i meant anways lol
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Post Tue Apr 19, 2005 1:54 pm

Ant made mention of one in this post : http://www.e30zone.co.uk/modules.php?na ... pic&t=2649

Not sure if it's N/A though.
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Post Tue Apr 19, 2005 4:56 pm

hoshy wrote:
Karan wrote:i think MAF is a big problem for 4 pots... even worse for cold running issues.... ive heard this from Pete..he said one of his customers had a m40 tuned to the hilt.. then a MAF conversion also...(sad i know!) and pete said it was dangerous cos it was so poorly setup

maybe if it was setup ok it would work....

Karan
There's nothing sad about tuning an m40!!!! It's all about the love dude!!!

My car came with that enigne. It's gonna stay with that engine.

(and it's gonna fly!)
agreed dude!

going FI is a different kettle of fish altogether....

however this guy had TDI powerengineering build him a bottom end, head cam etc..... genuine bmw motorsport bushes(these are serious expensive!) etc etc etc....and the car was undriveable and only slightly quicker! im sure u can agree that is the wrong way to go about things....

Karan
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Post Tue Apr 19, 2005 5:24 pm

if u could get 200bhp or more from a NA 2.5 someone would of done it by now! C2 2.5's are 190 i think. Or their sport pack of bolt on stuff could do this. Better off starting with a good early 2.5 lump with higher compression.
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Post Tue Apr 19, 2005 5:29 pm

So dale's was the highest powered 2.5 we ever had with 196bhp?
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Post Tue Apr 19, 2005 5:30 pm

well if his lump was tired n only making 140 beforehand... can you not with a bit of imagination add what he gained onto a healthy figure n then take a bit off maybe?
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Post Tue Apr 19, 2005 5:38 pm

H26 and C2 2.5 are quoted around the 190bhp mark yes. Neither use a 6 branch and both run on standard management using the crap AFM.

I think with say a MAF or standalone + 6 branch you could easily get to 200bhp. Remember also that a 284/272 is a wilder cam than both the Hartge and the Alpina have. Oh and they both never had BBTB's which we have seen give a few horses.
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Post Tue Apr 19, 2005 6:24 pm

Karan wrote: agreed dude!

going FI is a different kettle of fish altogether....

however this guy had TDI powerengineering build him a bottom end, head cam etc..... genuine bmw motorsport bushes(these are serious expensive!) etc etc etc....and the car was undriveable and only slightly quicker! im sure u can agree that is the wrong way to go about things....

Karan
yeah I s'pose. I guess it boils down to m5pilot's post earlier about tuning things properly.
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Post Tue Apr 19, 2005 6:53 pm

M5pilot wrote:So dale's was the highest powered 2.5 we ever had with 196bhp?

Does anyone know how much dale spent to make 196bhp??
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Post Tue Apr 19, 2005 7:36 pm

wilson325i wrote:
M5pilot wrote:So dale's was the highest powered 2.5 we ever had with 196bhp?

Does anyone know how much dale spent to make 196bhp??
Sssshhhh...you don't wanna know the answer, it'll make you :cry:

And Sal, Dales car had the cam in wrong first time round hence crappy HP, fooooking flies now tho!!! and then the NOS on top, does that count :lol: :lol:
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Post Tue Apr 19, 2005 8:06 pm

No NOS dont count!

I wasnt aware his timing was wrong. I think it only made 136bhp!

Cost? It was done the expensive, could be done alot cheaper though.

To do the same thing but use emerald it would cost Ԛ£2500.

But remember he has paved the way for all his future mods to be fully taken advantage of.
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Post Tue Apr 19, 2005 8:11 pm

Anyone know whats a pretty good figure for the IS? Im hoping to get one soon, and i dont want to leave it standard. Im planning on

Performance wise:

Chip
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Ive heard you can around 160 or more out of them if done well. That would be awesome :P
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Post Tue Apr 19, 2005 8:22 pm

Sam speak to demlotcrew he will tell u all u need to know about how to get some ponies out of these puppies. They are pretty good in standard form. Sodium exhaust valves and 4 branch as standard plus other stuff. They are not very diy friendly though

Problem is very few people cater for this engine in E30 guise as they made so few. 1000 left on our roads now maybe less.

Just make sure the head isn't gone on one it's the weak spot of these lumps. I had one what a screamer! Sterling silver too yummy!
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Post Tue Apr 19, 2005 10:17 pm

Turbo-Brown wrote:
Jhonno wrote:n when it was done the 2.5 would rev alot better due to bein more oversquare
Making an engine more over square won't make it rev any better, but if you had two engines of the same capacity and configuration, but one was oversquare and the other was under square, the oversquare would be more rev happy.

Unfortunately you can't really make an engine more hungry for revs without lightening the reciprocating parts and/or reducing the stroke.
the oversquare thing is fine in theory but not necessarily true in reality, as turbo brown said the more important thing is how well made / bananced the engine is.

example: the original integra type r engine (the 1.8 one) is limited to 9 grand (and makes its max power not far short of that) but is actually undersquare and quite a long stroke. friend had one and it's still a really smooth engine all the way to the top despite the long stroke
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Post Tue Apr 19, 2005 11:00 pm

just for the uninitiated (that's me :)

what's all this over/undersquare business about?
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Post Tue Apr 19, 2005 11:47 pm

fozzymonster wrote:then the NOS on top, does that count :lol: :lol:
no it bl**dy doesnt :lol:
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Post Wed Apr 20, 2005 2:26 am

I think a 24V DOHC head would help. Is there really no way to get one? Can't modify the M50 head or something? With that head I don't see why a 2.5L M20 couldn't get similar power to the 2.5L S14, and probably more torque. Of course that would require 6 throttle bodies and upgraded internals and all the other stuff you mentioned as well.

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Post Wed Apr 20, 2005 3:58 am

starting with an early high compression motor (custom high comp pistons would be desirable though, maybe 10.2:1?), i propose the following:

288deg cam
6 branch
aftermarket engine management (inc removal of afm)
BBTB
perhaps a few little tweaks to the head...


imo that would make 200 horses easily, probably more
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Post Wed Apr 20, 2005 8:20 am

hoshy wrote:just for the uninitiated (that's me :)

what's all this over/undersquare business about?
It's a bit of an odd term, but it refers to the ratio of the bore to the stroke.

If you had an 84mm cylinder bore and an 80mm crank throwm that'd be oversquare. If you had the same crank but a 75mm bore, that'd be undersquare.

If you had 80mm bores and an 80mm crank throw, tha'd be a square engine.

If you're designing an engine, you'd probably err on the side of oversquareness for a given capacity as the larger bore lets you fit larger valves in which makes the whole shooting match more efficient.
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Post Wed Apr 20, 2005 8:21 am

astondg wrote:I think a 24V DOHC head would help. Is there really no way to get one? Can't modify the M50 head or something? With that head I don't see why a 2.5L M20 couldn't get similar power to the 2.5L S14, and probably more torque. Of course that would require 6 throttle bodies and upgraded internals and all the other stuff you mentioned as well.

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a company developed a 24V m20 head but gave up because the m50 came out, cost was fairly high for it you see.
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Post Wed Apr 20, 2005 8:30 am

The early engines have CR of 9.7:1 (or there abouts) which is high enough. Even in stock form they have proven to make 175 bhp.

Adding a 284 cam (288 may require piston modifications - im not sure though),BBTB, 6 branch and stand alone management + head work would defo see 200bhp and over.

Head work actually works. Hartge used to use a realy thin head gasket on the H26 conversion to get the compression up but the gasket proved to be unreliable. Therefore they reverted back to a standard head gasket and did more head work instead and got the same results.

I spoke to bexleys about this and they said they have come accross 200+ bhp 2.5's and they are on par with the 2.7's. Only difference is that the 2,7's are more versatile because of the extra torque but flat out theres nothing in it.

They have in the last year done a MAF conversion to a 2.5 with a cam and 6 branch. They achieved just under 200bhp.

Its alot less hassle than going the 2.7 route straight away to achieve the 200bhp mark. 2.7 can always be done at a later stage.
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Post Wed Apr 20, 2005 12:44 pm

Sal im at Brunel Uni, and do you know where birds is?

Anyway ive been in to see them with a whole load of cash for the Hartge H3 conversion on my M42. 'Yes' i said 'dont care, have the money i want it done'. 'Okay' sir says one of the guys, let me email Germany for the parts.

:cry:


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Post Wed Apr 20, 2005 12:51 pm

How much is "a lot" exactly... :eek:
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Post Wed Apr 20, 2005 1:00 pm

Engine H3-1.8 160hp Conversion
Application : 318is M42
Installation cost : Ԛ£784.80
Parts cost : Ԛ£1,255.49


?
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