Tuning for larger Intake Manifold

[McCoy]

OK, so I have this new 02 induction manifold that I will be installing soon enough and was certain that I would have to revisit the ECU for some minor adjustments. I thought I'd check with JWT first to see if they could do this for me.

This is the response that I got yesterday, I understand the basics of the MAF, but have also seen a few dynos that show a leaner A/F up top after adding a larger IM.

Thoughts on this... I guess I can just dyno the car after adding the IM and see where I'm sitting at, and go from there.

.

Hi Monty,
When you change the design of the intake manifold, any increase in
air flow from this will be seen by the MAF sensor so there would not
need any change to the program in the ECU for this. Other parts that
also do not directly effect the ECU program are cylinder head porting
changes, exhaust system changes and the intake tubing/intercooler
dimensions. Things that do require a program change are injector
size, MAF type, compression ratio and octane of fuel being used.

If you want to upgrade to the Nismo 740cc/Z32 MAF program, we can do
this on an EPROM exchange so you wouldn't need to send us your entire
ECU. We can upgrade and send you a replacement EPROM with the
correct version of software you need for $100.00 plus a refundable
core deposit of $250.00. Then you send us back the previous EPROM to
get your core deposit back.

I emailed Jon at 02Induction to get more details on the IM, since I bought it 2nd hand. This was his response on the IM.

I built that manifold as a prototype and never got any feedback or dyno
info on it????? It has shorter than stock runners fully tapered to large
velocity stacks, large plenum. That's about all I can tell you.

Same engine but due to the hood clearance issue the runners are longer
and have the bend before the injector. The FWD manifolds have pretty
much a straight shot to the valve. Same taper in the runners but heavily
shaped internally before the injector. Similar but larger plenum than
the FWD and that one has the huge Q45 throttle body flange. Basically
the manifold is designed for Max. Hp without having to make a custom hood.
Thanks, Jon

[Epstein]

JWT is telling you the same thing that I would tell you. That's the beauty of a mass-flow system.

Post up some links to the the dyno plots that lean out up top. There are several reasons that it could/would go lean including running out of fuel/maf and reading from a different part of the map.

[McCoy]

Thanks for the response, this is what I originally had thought, but was getting mixed comments. The original owner of this IM was seeing a lean condition and it could have been due to the 50lb injectors that he was running... he dynoed around 410whp.

I'll see if I can dig up the other recent dyno that was posted on SR20forum.

I want to throw this IM on now, but will probably wait till I have my T3/T04 setup here and try to do it in a few steps and dyno in between adding the turbo and the IM.

[Epstein]

Thanks for the response, this is what I originally had thought, but was getting mixed comments. The original owner of this IM was seeing a lean condition and it could have been due to the 50lb injectors that he was running... he dynoed around 410whp.

I'll see if I can dig up the other recent dyno that was posted on SR20forum.

I want to throw this IM on now, but will probably wait till I have my T3/T04 setup here and try to do it in a few steps and dyno in between adding the turbo and the IM.

That lean condition sounds probable. I've datalogged a rom-tune car running 550cc (roughly 50#) injectors, and we were seeing 95% duty on a 360whp setup.

Just be sure to post results!

[Def]

The fueling will be fine like Epstein said(unless you run into the limits of the fueling system), but the timing will be a couple of degrees off from "optimal" due to going to a higher load cell.

[float_6969]

IDK if this will be applicable to your specific manifold, but I can tell you that when my friend switched from the stock S15 SR intake manifold, to the Freddy intake manifold, we initally lost power EVERYWHERE and we had to not only had fuel, but alter the timing A LOT to get his power back. Now this is with an SDS EM4-F (speed/density) so the fuel had to be manually altered, so you shouldn't have to worry about that with the MAFS setup, but the MAFS isn't going to fix your potential timing problems.

I still haven't figured out why we had to alter the timing to get the power back. I'm guessing that the increased air flow altered the way the flame front propagated through the combustion chamber, which forced a change in the ignition timing.

[Jonty]

I'm digging this up as I'm doing some inlet manifold calcs with a view to designing/building my own... seems to me the reason that the FReddy manifold lost power everywhere and needed spark to get it back *could be* that it's a crap manifold and flows worse than the stock S15 (S14 in uk had the same) manifold, but because of the loss of flow the cylinder pressures were correspondingly lower and so you can wind in more spark before det occurs.

Does anyone know any back to back dyno results of IM swaps that they can link in here? I'm interested to see what is on the market and also whether the changes my calcs are predicting as inline with the real life results.

Cheers,
Jonty

[Def]

Every GReddy mani dyno I've seen gains power above about 6.5k RPM. It'll lose it down below that.

It's probably not an optimal runner length, but it's a cheap way to get more power up top. Most FReddys also need some clean-up in the runners and on the TB inlet port. Make sure you have no obstructions and a nice taper on both.

[Equinox]

Reakon you'd be able to dig up any of those dynos Def? Interested.

[McCoy]

What I'm finding funny about this thread being dug back up is that I'll probably have this IM back in my posession by winter

[Def]

Reakon you'd be able to dig up any of those dynos Def? Interested.

I remember seeing them from back in the Freshalloy days before that place sucked. Might help to search on there in the 240SX Advanced section.

[Jonty]

What I'm finding funny about this thread being dug back up is that I'll probably have this IM back in my posession by winter

I nearly did that with my last track car...! It'd be good to see if you get any improvement, although by then I hope to have already got my own IM sorted... but you never know with these projects!

Def I'd be interested to see those graphs, I can't seem to get on Freshalloy at the moment