Dbilas vs Extruabody ITBs

[nando]

The dbilas ones he posted are 2,075 euros. That's over 2,800 dollars. Then they need to be shipped here and import duties paid. It might end up being more than $3,000.

Did you even read the thread?

[digger]

The dbilas ones he posted are 2,075 euros. That's over 2,800 dollars. Then they need to be shipped here and import duties paid. It might end up being more than $3,000.

hopefully by now everyone knows the dbilas kit is uber $$$ and doesn't live up to expectations. it should have been apparent several years ago infact. i used elements of the kit to get mine up and running and its fine for that but i have moved onto better things.

[ForcedFirebird]

neither of the two IMO.

steer clear of dbilas, have seen bad results on many builds. cant see extrudeabody being much better

www.racehead.com.au

alot cheaper and better, need to make an airbox like you would with extrudebody.

see my sig

Just dyno'd a set of Extrudabody 45mm ITB's on an m20 yesterday, and a couple months ago did the RHD set. Both cars were high mile stock 2.5's with a rebuilt head and 272 cam - both cars were within a couple HP of each other, the RHD car has headers, dual exhaust with x-pipe, twin resonators, light porting, larger valves and flow tested. Extrudabody car has a full stock exhaust.

RHD dyno:



Extrudabody dyno:

[digger]

yes, much the same peak hp but the RHD smashes the Exrudeabody in the midrange as you would expect, obviously other differences exist but the boring flat torque and lack of hump in the midrange will more than likely be the ITB, they just dont "tune" where they are supposed to as they are mismatched to the engine combo

Rpm / tq RHD / tq EXT
2500rpm / 135 / 135
3000rpm / 143 / 130
3500rpm /145 / 132
4000rpm / 150 / 133
4500rpm / 160 / 135
5000rpm / 158/ 135
5500rpm / 162 / 145
6000rpm /152 /145

At 4500rpm the RHD has 25 ft-lb advantage which is 18.5%

shame its not a direct comparison on the same engine etc but sometimes that is a rare luxury, nevertheless great info

it would appear that atleast with extrudabody you get a topend gain unlike dbilas, this is likely due to better manifold (rowlands >> dbilas)

[ForcedFirebird]

Based on experience, the headers installed have never seen a HP gain, only TQ. Couple that with the better exhaust and longer trumpets, I can see why the TQ was better on the RHD kit. If the Extrudabody car was staying N/A, I would advise the owner to have us install longer trumpets and make another go at the dyno, but he is dead set on a turbo, so those efforts will be put into a nice plenum.

Here is a good read about trumpet length and the effects it has on tq... http://www.emeraldm3d.com/articles/e...length-intake/

[HennaE30]

Based on experience, the headers installed have never seen a HP gain, only TQ. Couple that with the better exhaust and longer trumpets, I can see why the TQ was better on the RHD kit. If the Extrudabody car was staying N/A, I would advise the owner to have us install longer trumpets and make another go at the dyno, but he is dead set on a turbo, so those efforts will be put into a nice plenum.

Here is a good read about trumpet length and the effects it has on tq... http://www.emeraldm3d.com/articles/e...length-intake/

Sorry to thread jack but it was something I had always wondered. You said your customer was doing an ITB Turbo M20? What kind of extra gains do you see from adding ITBs to a turbo? I had thought about it before but wasn't sure if there would be much gain from doing it. Do you have any pictures of the ITB turbo set up? I googled it and couldn't find anything.

[ForcedFirebird]

Sorry to thread jack but it was something I had always wondered. You said your customer was doing an ITB Turbo M20? What kind of extra gains do you see from adding ITBs to a turbo? I had thought about it before but wasn't sure if there would be much gain from doing it. Do you have any pictures of the ITB turbo set up? I googled it and couldn't find anything.

We will make a thread after it's finished. Not sure there's any public info, we just do what the customers ask.

There would be benefit, albeit not HUGE. With a large plenum and ITB's, the plenum will stay charged and that compressed charge will only have to travel a few inches to enter the chambers. In a typical manifold, the TB will close off the charge pipes and the manifold will be in vacuum and need to be refilled. Doubt there would be much, if any, peak power gains, but the throttle response will change as well as lower RPM power.

[HennaE30]

We will make a thread after it's finished. Not sure there's any public info, we just do what the customers ask.

There would be benefit, albeit not HUGE. With a large plenum and ITB's, the plenum will stay charged and that compressed charge will only have to travel a few inches to enter the chambers. In a typical manifold, the TB will close off the charge pipes and the manifold will be in vacuum and need to be refilled. Doubt there would be much, if any, peak power gains, but the throttle response will change as well as lower RPM power.

Ahh alright that makes sense. Definitely interested in the thread. Do you in your opinion think it is worthwhile?

[ForcedFirebird]

Ahh alright that makes sense. Definitely interested in the thread. Do you in your opinion think it is worthwhile?

Not sure. In my opinion a Spec e30 has plenty of power to be a blast to drive at 10/10th lol.

either way it's going to be a fun build.

[digger]

Sorry to thread jack but it was something I had always wondered. You said your customer was doing an ITB Turbo M20? What kind of extra gains do you see from adding ITBs to a turbo? I had thought about it before but wasn't sure if there would be much gain from doing it. Do you have any pictures of the ITB turbo set up? I googled it and couldn't find anything.

ITB are more about throttle response and driveability, the throttles themself do next to nothing for WOT power, its the change in runner alignment, diameter, length, plenum size, aif flow distribution, flow efficiency etc that come with the throttles kits that change the power curve

[HennaE30]

ITB are more about throttle response and driveability, the throttles themself do next to nothing for WOT power, its the change in runner alignment, diameter, length, plenum size, aif flow distribution, flow efficiency etc that come with the throttles kits that change the power curve

What do you mean by "runner alignment"? Like orientation in regards to the head/other runners?

[digger]

What do you mean by "runner alignment"? Like orientation in regards to the head/other runners?

how well the manifold that bolts to the head aligns with the cylinder head port angle, the RHD manifold is basically an extension of the port, the dbilas comes in at a different angle

RHD



DBILAS



its pretty fundamental but still alot of aftermarket stuff misses the mark

[HennaE30]

how well the manifold that bolts to the head aligns with the cylinder head port angle, the RHD manifold is basically an extension of the port, the dbilas comes in at a different angle



RHD







DBILAS







its pretty fundamental but still alot of aftermarket stuff misses the mark

Ahhh alright. That makes sense. Thank you.

[E30SPDFRK]

Has no one bugged Jenvey into making a kit for M20's yet? They are often considered the best for induction systems.

[ForcedFirebird]

Digger, the only reason I revived this thread was because the Extrudabody has always been doubted, or bundled in with the other major mfgr's for power guesstimates. Even with the mis-matched Rowland carb manifolds, they did produce in the end.

Has no one bugged Jenvey into making a kit for M20's yet? They are often considered the best for induction systems.

I tried. I was the one who did all the R&D for the 24v kits and bugged them about the m20, instead they did m10 SMH. In honesty, they will be out priced by RHD for similar results. I can say, though, their quality is superior - spin castings, linkage etc are all top notch.