To start off, the car is a 93 EG w/k20a2. It made 224 hp with RBC, CAI, WS2 Catback, Ktuned Headers, return fuel system, 70mm BDL throttle bodie and KPRO.

Then I supercharged it, added DW 800cc injectors, DW 300LPH fuel pump. Car made 304hp, 320 hp on meth.

Decide to turbo the car. Added K20a3 mani, port matched to throttle bodie, log mani, Precision 6076 BB turbo, 3" downpipe, 3" IC piping, intercooler good for 600 hp.

Went to have it dynotuned at the same exact place, car made 260 hp @ 5300 rpms and flat lined. Before throwing it on the dyno, we did a compression check and it was mid 180's to low 190s across all cylinders.

So we started troubleshooting on the dyno. We took the intake off, made a little extra power but still flat lined at 5300 rpms. We ran it open downpipe, still flatlining. We then did a pressure test, found 2 leaks, fixed them, still flatlined @ 5300 rpms. We thought maybe the map may be corrupt. Tuner made a new map, still wouldnt make any power. AFR's were 11.9s. Adding ignition made zero power just leaned it out. Car wasnt spinning on the dyno either. So the day was a loss. It wasnt the dyno, because the next guy who got tuned, made 550 whp right off the trailer.

I know the log mani isnt the greatest but people still make 400+ hp with them. The only thing left that I believe could be the problem is the intake manifold. It is an A3 mani. But then again, turbo k20a3's have made 380 hp on this dyno with the stock intake mani.

We did a leakdown and it checked out fine. Also we arent getting any CEL's. We have no where else to look but possibly the intake manifold. BTW the turbo/bov/wastegate is brand spanking new, boost is solid, fuel pressure is solid, and kpro is taking the changes.

Does anyone else have any ideas why the car would be flatlining at 5300 rpms?

 

Is your wastegate dumping by your turbo inlet? Could be sucking up dirty exhaust gas which is killing power right where your wastegate opens up

 

Sadly no, I wiah it was that easy. Could it be the wrong plugs? I'm using a 2 step colder iridium when it was supercharged and i just read I should be using coppers. NGK 4091s is what I read that was recomended

 

How does your log manifold look like?

 

Like the cybernations. The runners are big!

 

Spark blow out?

What are your plugs gapped at?

Try running one heat range colder than stock, take the gap down to like 20 thousandths, and index them so the open side is facing the exhaust ports.

 

I suppose its a possibility.

Changing the plugs and gapping them down to .025s along with indexing them. The ones in it now are iridiums and are gapped at .043's from NGK.

Really wonder if this intake manifold is the holdback....

 

Is it stumbling or the power curve just falls flat?

What happens when you turn the boost up?

It's not the intake manifold, something else is going on, you can make more than 260 whp on any intake manifold

 

spark blow out will stutter not flat line but .043 is a huge gap try .025 and see what happens. what is your boost gauge reading? this sounds like a wastegate issue to me.

 

Power curve falls flat and its rough too which was prolly the spark blow out. That's fixed but the car is easily still down 100 HP. Put NGK 5368s in, gapped them to .023s and also indexed them. Car runs smoother but still stops making power at about 5k rpms which is about exactly when it hits full boost and in my oppinion that's pretty laggy for this 6076.

I also don't think It's the intake manifold either. Just have absolutely nothing else to check next.


Gauge reads 13 lbs, KPro reads 12.2-12.8, holds boost perfect. And when i turn the boost up, holds great. Even when we had the boost leaks on the dyno, the turbo kept up so its not the wastegate.

Also went out and did some datalogging tonight. It's not pulling ignition, and afr's are dead on. I added 4 counts of ignition into it and the afr's didn't do much. Didn't really feel any different either, which was the same it was doing on the dyno. TPS, map, CPS, and all the other sensors are reading just fine. No knock. Also, all the injectors and coil packs are firing. Fuel pressure regulator is fine. Pretty much have checked every possible route. Car runs strong and idles like a brand new car. Valves are whisper quite.

Lost in the dark.

 

Are you sure that Vtec engaging?
check wiring or broken wire

 

I can guarantee you its not the K20A3 manifold nor is it the log manifold. I believe it has something to do with the VTEC system, since it stops there. Is your VTEC working properly?


I do have a question though; Why a K20A3 intake manifold? If its because its plastic and maybe colder intake temps thats pretty smart.

 

X3 id check your vtec. Whats it set at?

Also what injectors are you using?

 

Im pretty sure hes still using the DW 800cc injectors, I dont see why he would need to change them.

 

Have you tried running the non vtec lobe on further past 5200-5300rpm say 6200-6700rpm? If it keeps making power i would try dailing out the overlap of your cams when you turn on vtec. I cant tell you whether to advance or retard anything because these engines run opposite to my F20B but i'd try that first as that is where i found big gains doing this on my engine.

 

VTEC works perfectly fine. It's set at 5200 & 5700. I've tried it higher, no change. Injectors are fine, they're at 52% duty cycle from 5k-8k rpms, proving the car isn't making any more power past 5k.

Got to thinking about it last night. It has RBC cams, stcok springs. The only thing left that it could be is valve float. Google "valve float dyno" and under images, its really similar

 

Sounds like it could def. be a valve overlap issue, try installing adjustable cam gears, and dial out all the overlap, or just switch back to stock cams.

Stock cams will make 400 whp.

 

Thanks to uour comment, we can definitely rule the manifold out. I was mistaken. It is an 02-04 rsx type-s manifold. I was told it was an a3 but its not plastic.

 

Post a log.

 

This is beside the point of helping you fix your car but ep3 has a k20a3 with aluminum intake manifold.

 

I'll post one tomorrow. Out of town rt now.

That's what I thought but I looked on eBay at k20a3s and they had plastic manifolds. Here's a pic of the manifold on the car.

 

On your dyno A/F ratio plot how does it look around that area? No random lean/rich spikes? You may have to highlight that area to make the resolution better to see if there are any spikes around there. I also have a similar problem on vtec change over with my F20B, there is a big flat spot. My A/F datalog reading shows random dips and spikes after change over so has lead me to believe that i need to swap out my valve spirings to something stronger. I think the type S/Euro R cams i are using may be to aggressive for the stock valve springs causing slight float. My A/F's are as smooth as when not in vtec right up to 7000rpm where power is has nearly fallen right off.
You may possibly be having the same problem...

 

the k20a3 out of the ep3 uses the same prb manifold as the rsx-s. the base rsx k20a3 uses the plastic manifold. but why would you downgrade from an rbc?

 

There will be dips regardless. But its pretty damn smooth. It's gotta be a valve issue.

None the less, it should still make 400+ HP. The RBC was sold after I supercharged the car and got this intake mani for dirt cheap. Prolly gonna throw an RBC on it eventually anyhow.

 

gotcha. was just trying to clarify the manifold differences for you.