Fully built engine.... but stock exhaust manifold. What benefits to switching?!?!

[bsbllfit7]

So i have a fully built bottom end and have using an older fp green on my setup. My setup is fairly knock friendly on 92 octane pump gas. I am currently using the stock 2g unported exhaust manifold. Is there any way that by swapping my mannys (i have a older ported slowboy manifold) on that somehow backpressure in the manifold will change and possibly reduce my knock? Also obviously i will be getting more air flowing through the manny, but will it reduce spool time? Just some questions that i tried searching for but couldnt find a direct answer.

 

[dboyle23]

I don't think that is really going to help your knock. I would throw on a that sbr manny and then tune for no knock.

 

[1990AWD]

Edit: never mind, read it wrong.

I don't think the manifold will help with knock, that has more to do with what's going into the engine (intake & fuel).

 

[bsbllfit7]

But i also read that having the exhaust manny as a bottlekneck can cause backpressure inside the manny and engine because the exhaust cant get out as quickly as its coming in? Just seeing if there was truth to that reading. Thats why sometimes when people get cams (which i also need) they reduce knock.

 

[1990AWD]

But i also read that having the exhaust manny as a bottlekneck can cause backpressure inside the manny and engine because the exhaust cant get out as quickly as its coming in? Just seeing if there was truth to that reading. Thats why sometimes when people get cams (which i also need) they reduce knock.

Exhaust backpressure is an issue, but since you have a Green, you have the TD06 turbine which flows quite well. I don't think the 2g manifold is that big of a restriction, a manifold would help, but that's if you have money.

I personally have never heard of cams reducing knock but I wouldn't be the one to ask about that.

 

[bsbllfit7]

I only heard that because when i went to english racing they said my setup at that time was super knock happy. They said I have some major restrictions in the head and the first thing to get to replace that would be the cams. They said that should help with my knock so i researched it and found that it has been found to help in the past. What i really need to do is get a new ported head to help airflow because im sure its not very happy as of now. I get knock with below stock timing on 20psi on this setup as of now without mixing in some e85. With e85 i can get 22-24psi (boost creep) and almost stock timing. It is a 2.4l and i know that they dont require as much timing but how much should that change from a 2.0 to a 2.4l???

 

[97DSModded]

Cut the divider out of the exhaust manifold. I'm running a fp3065, and it seems like it spools a tad quicker with the divider gone.

Edit: Btw, you don't need a NEW ported head. All you need is a good machinist. Become friends, and you can save a lot of mulah.

The stock 2g exhaust manifold shouldn't be a problem with your setup. They should flow well enough up to 500+

 

[bsbllfit7]

So what could be the limitation that is causing me to knock? Obviously 92 pump gas isnt the best. Would the intercooler efficiency come into play here? Im using the PR kit which is supposed to be pretty efficient for my goals.

 

[bsbllfit7]

anyone have any other thoughts on this? Trying to do the proper things here. I was doing some research and also increasing the cam overlap with adjustable gears has been known to help. Any info on that?

 

[slowauto]

What are you using to tune it and whats your wideband reading when you go into boost?

 

[bsbllfit7]

Link v3lite and my AFR's are about 11.3-10.9 all through my third gear pulls

 

[1990AWD]

If you have Link how about you post a log. I can't believe you have had Link and not posted one yet.

 

[dirtysouthpinoy]

reducing timing, adding fuel, lowering intake temps (meth) all help reduce knock. Dont think a exhaust manifold will reduce it. I see you have dsmlink, post a log of your knock so we can see whats causing it.

 

[bsbllfit7]

So just dyno'd the car today and we realized my LC1 is miscalibrated. I was seeing 11.0 afr's and it was actually coming out to 12.3. I will be taking the o2 out and recalibrating today and going to go straight pump gas and see if it changes anything!

 

[dirtysouthpinoy]

well theres your problem way to lean for 92 octane.

 

[bsbllfit7]

Haha ya i agree, i had no way of knowing the lc1 was miscalibrated tell i went and got it dyno'd. Well she made 412.5 awhp and 434.5 awtq with 0 counts of knock. It was a mix of e85 and pump. about 5 gallons e85 to a the remainder of the tank being pump.

 

[bsbllfit7]

Just re calibrated the lc1 now and sure enough my afrs were 12.3-12.5! That will make a huge difference tuning that down to 11.1! Time to add some timing back in!