318is turbo with itb's

[dwtaylorpdx]

that bit of "forum wisdom" gets passed around a lot. direct experience has caused me to disagree with it.

put simply, combined with an exhaust, MarkD chip and 24lb/hr injectors, the dbilas itb/alpha-N setup provided -noticeable- gains on a stock m42 longblock. most noticeable is a willingness to wind out all the way to 7k rpm. think about it- replace the 80's-tech flapping-door AFM with a nice big open intake, and get rid of the first-generation intake manifold for something designed to put the powerband at the top of the tach, and the engine is going to flow more at high RPM. this should not surprise anyone.

i don't know who started the rumor that ITBs are "only worthwhile on built/race engines", but they were wrong. if anything, the opposite is true- if you've spent the money on headwork and cams but are still using the AFM and e30 intake manifold, you are probably leaving power on the table.

Ok let me say this a little different.
Direct experience for me has been that ITB's don't add to my driving experience in most street cars. Most of them that I've driven with motorcycle throttle bodies make lots of cool noise but They don't seem to dyno out higher power numbers, but they sure move the powerband up! Which  is handy if thats what you want to drive.They cause issues with smog and I live in a green state so I'm stuck without them.

I have a E36, M42, so I have no trouble winding up to 7K (or as close as the rev limiter allows. So the reference point is critical, comparing a OLd E30 manifold to ITB's I could definately see it. From my manifold to ITB's I would not expect to see a big power number jump, Without at least a cam.
And the engine shop that does the work on the race cars I deal with has dynoed the flapper valve AFM several times including a M42 and it really does not affect power until you up in the 6000 range, which my street car doesn't. If its a pure track car now that's a different story.

Basically I think ITB's are application and installation specific, do the work right and tune the package and there may be something there. But I'd still spend the money on the cams and pistons and head-work first, then front it with the right intake and exhaust systems.

Dave

[deekay]

if we were talking about an m20 i'd agree.

the m42, however, already has cam out to 7000rpm as you've mentioned (and my markD chip will go there also), and 10:1 CR.

it's no skin off my nose if you disagree, but i don't regret spending $1200 on a set of dbilas' which were engineered to work with this engine (not a grafted-on set from a sportbike) and not two or three times as much for slightly more compression and slightly more cam; considering that radical changes to both are also ruled out by living in CA or OR (and are also not as easily reversed come smog-check time).

finally, the argument that the e36 manifold is somehow superior isn't really borne out by the fact that a.) peak horsepower is the same and b.) metric mechanic didn't bother to use it for their rally/race builds.

none of this is to say i'm not going to dig into the engine at some point in the future; it just makes more sense to me to eliminate external bottlenecks first.

[dwtaylorpdx]

I didn't say the e36 manifold was superior, i just said I don't expect the ITB's to raise the HP number "much", without some extra parts.

I can see how if you get a set of ITB's that are engineered to work on the car you'd get some good throttle response. and likely more snap up high.

Metric Mechanic does not likely install ITB's on stock engines either.... Do they even build stock engines?

Its all a question of $$ per HP. and it can be a chicken and egg problem, youll need a decent cam to really light up the ITB's and you need ITB's to really exploit a good cam.

Anybody ever done a dyno compare between the E30 and E36 intake manifolds under boost?

I'm finding smog is less of a deal for me now that Oregon went back to no under hood just a sniff test. For Pre-OBDII vehicles! Whooo Hoo! Gotta like the 95....

Dave

[strypt]

However, the evidence seems to suggest that they are a good idea, as with the car linked above, i read somewhere that it is making signifigant hp. (400+bhp)
http://s90.photobucket.com/albums/k267/Bonje_80/318is%20turbo/

528 rwhp But he didn't like the engine response so he's re-doing a lot of stuff to improve that. Here's the build thread http://www.pure-pf.com/phpBB2/viewtopic.php?t=4425

[dwtaylorpdx]

Looks serious!

Dave

[kevins08]

what holset is he running?

[strypt]

It's a heavily modified mix between HX40 and H1E.

[fiftytakedowns]

if we were talking about an m20 i'd agree.

the m42, however, already has cam out to 7000rpm as you've mentioned (and my markD chip will go there also), and 10:1 CR.

it's no skin off my nose if you disagree, but i don't regret spending $1200 on a set of dbilas' which were engineered to work with this engine (not a grafted-on set from a sportbike) and not two or three times as much for slightly more compression and slightly more cam; considering that radical changes to both are also ruled out by living in CA or OR (and are also not as easily reversed come smog-check time).

finally, the argument that the e36 manifold is somehow superior isn't really borne out by the fact that a.) peak horsepower is the same and b.) metric mechanic didn't bother to use it for their rally/race builds.

none of this is to say i'm not going to dig into the engine at some point in the future; it just makes more sense to me to eliminate external bottlenecks first.

I always read about hte metric mechanic this, enough airflow that, but I'd bet some serious dollars that Metric Mechanic is not fabricating ITBS because of the cost to make one vs the profit they get out of it.  But I'd like to see someone with the metric mechanic motor, swap on some ITB's and really see a difference.  I mean if ITB's arent better, then why are they on the s42 race car, the s14 with a 7k redline, and all the euro s5x s3x motors?

[Warsteiner]

I always read about hte metric mechanic this, enough airflow that, but I'd bet some serious dollars that Metric Mechanic is not fabricating ITBS because of the cost to make one vs the profit they get out of it.  But I'd like to see someone with the metric mechanic motor, swap on some ITB's and really see a difference.  I mean if ITB's arent better, then why are they on the s42 race car, the s14 with a 7k redline, and all the euro s5x s3x motors?

WE shall see shortly. I will have my motor running very soon.  Not a MM motor but a stroked motor with DiBilas' ITB's and Megasquirt. I'll do a complete write up on it. A couple of trick things to make it different than everyone else's motors.
As far as the S14, it revs to 7800rpm with a chip and some with shim under bucket can go to 8500rpm with no issues.
Just going from 46mm to 48mm ITB's, (which is an almost 10% increase in cross-sectional area), on the S14 makes a big difference so going from a Throttle Body to ITB's, I'm gonna say that there should be a good gain.

[JulianS]

Bonjes engine (the one pictured) is a 2.0litre engine... The first setup gave 615whp on bioethanol and 1.6bar boost he is going to dyno it with the new setup soon...

I have a set of s50b30 itb's and a custom alloy intake coming soon. It costs me about 1100 eur complete with the custom intake plenum and a dbilas system costs about 1700eur in norway so i am satisfied:)

I think it will be a much better setup than with the standard intake manifold... I ran 1.6bar boost aswell and hoping to do that with my new engine to and hopefully put out 350whp on 99 octane... think it is possible, this car (http://www.pure-pf.com/phpBB2/viewtopic.php?t=18869&start=0) managed 334whp on 1.5bar boost and 95 octane

[strypt]

... The first setup gave 615whp on bioethanol ..

No it did not, it was 528 whp. The 615 hp posted dyno sheet is recalculated engine hp from estimated drivetrain losses.

[littleboyblues]

Well heres some food for thought.

 Itb's needs cams. In a n/a situation these cams have lots of over lap and duration. However, i recall from somewhere that turbos do not respond well to lots of overlap. So...whats the solution for a turbo with itb's.

Now most of us drive street cars and there have been alot of turbo builds around 200 bhp. Now on the street, a flat torque curve is nice rather than no power anywhere except right at the top. So...long runner so help with the bottom, a medium turbo to hold the middle and mid-top, and Itb's to keep it strong at the top. So...the big problem here is cams cause im mixing n/a and turbo logic together. Im just throwing out the idea, so...rip it apart guys

[dvmotorsports]

WE shall see shortly. I will have my motor running very soon.  Not a MM motor but a stroked motor with DiBilas' ITB's and Megasquirt. I'll do a complete write up on it. A couple of trick things to make it different than everyone else's motors.
As far as the S14, it revs to 7800rpm with a chip and some with shim under bucket can go to 8500rpm with no issues.
Just going from 46mm to 48mm ITB's, (which is an almost 10% increase in cross-sectional area), on the S14 makes a big difference so going from a Throttle Body to ITB's, I'm gonna say that there should be a good gain.

Post pics of build please.

And does anyone know if that build link is Swedish or Austrian? I'd like to run it through a translator.

[strypt]

And does anyone know if that build link is Swedish or Austrian? I'd like to run it through a translator.

If you are talking about the thread I linked, it's Swedish.

[JulianS]

615,5 hp at the wheels: http://www.pure-pf.com/phpBB2/viewtopic.php?t=4425&postdays=0&postorder=asc&start=209