I have my s4 t2 with s5 rear plate street ported with 9.0 rotors ra superseals new springs side seal springs and all clearenced triple checked it all when I put it together . leaving dyno other day just made 386whp with bad ignition cut up . around 6700rpms car would fall on its face so I figured new plug wires . just put in a set of new plugs before dyno . did one hard 1st -3rd pull. Top of 3rd i felt loss of power . and I thought maybe I killed plugs again . did a compression test and it was 60 60 0 .put atf in the motor still nothing thinking it was a stuck seal took my turbo off to inspect seals there all intact and move in and out fine . all clean inside . I'm lost for ideas has to be a side seal right? Car barley holds an idle

 

when you pull it apart look for damage on the top edge of the intake ports. if you go too far, the side seal isn't supported and can drop into the port, which will break them

 

Well, your compression test indicates one side seal completely stuck down in the groove and possible side seal, corner seal and/or apex seal damage on the rest of the faces.

Its gotta come apart, so you will see the carnage soon enough

Are you certain the hesitation wasn't detonation?

 

True, but remember when you look at the top edge of the port that a broken corner seal will drop into the port and gouge the closing line too.

Usually if there is a problem with the ports it causes problems at low rpm when the side seals have more time to drop in on extension.

I have found with the stronger apex seals in my engines it just means detonation takes out the corner and sideseals and warps the apex seals and crack the plates.

 

Yea my port job isn't that serious I have pics . I'm lost on how a side seal went .no detonation as far as I know my car was nice and rich on dyno even have vids . I did hit a bump and I was low on gas about 1/4 tank when I did the pull

 

Its actually 60-0-0 so idk guess i gotta pull it out

 

Hw much did you drive the car before it was tuned?

 

All day . timing was off for at least 500,miles of it fixed timing and car felt completely different so we took it to dyno . did at least 15 pulls . and at least 5 highway pulls before that happend . sucks

 

you drove under boost without being tuned?

 

Base map street tube before dyno . didn't hit boost till about 500 miles in the car

 

I ment as in we did all the pulls after dyno . it gave up 2hrs afterdyno

 

just my opinion- but you did the damage driving the car and boosting before it was fully tuned

what is the fuel system?

 

720s1600s for an dwalbro 255 . it should have blown at 300;miles if that's the case

 

My experience with my 720cc/1600cc and a Walbro 255HP is that the fuel pump will drop pressure and cause hesitation/detonation and you won't see it in the AFRs.

I swapped out to a '044 after describing what my car was doing to Bryan@BNR and taking his advice to upgrade the pump. The hesitation went away.

Also, what fuel and boost.

Again, detonation feels like hesitation. On 9:1 rotors and pump fuel you can get auto-ignition from 12-22psi depending on many factors.

With 386RWHP I would guess you are about 14-15psi boost.

Little things like the gas station pump not switching fuels right, the additive not getting added, recirculating crank pressure to the intake, water in the gas pick-up area, etc etc can lead to detonation at 14psi on 9:1 rotors.

 

it should have blown at 300;miles if that's the case

Hard to predict. Last time my set up went it was a bad batch of gas that was causing major hesitation (knock sensor pulls timing).

I kept racing anyways and the car had an oil leak after that.

Next race event and after driving on the street (fresh gas no more hesitation/detonation) the leak was getting worse so I took a hard look and found-

Cracked rear iron at the oil filter mount (reinforced S5 block).

Took the engine apart-

3mm Apex seals cracked in half, but still in place. Sideseals broken, corner seals broken.

Everything still in place and had not caused interference issues even while racing- I got really lucky.

 

Wow that's crazy and it was 16psi with it cutting up at 6700rpms cause of ignition . should have made easy 400whp it had shell 93 . I dont want this to happend again it must have detonated . **** sucks . all my apex seals are fine 95 psi on both rotors . housings are nice and clean from what I can. See on exhuast side

 

Check the rotors real careful too make sure you didnt dent one
I learned the hard way driving with a "quick street tune" you need to drive zero boost and make sure everything is operating before turning things up.

 

+1. you need to walk before you can run. so start the tune in vacuum, then 0psi, 2psi, etc, and work your way up. just slapping it together and running 15psi on a "basemap" is just asking for a blown engine

 

Not really I didn't have no boost till about 400 miles almost

 

you also said timing was off for almost 500 miles

Im giving my advice because I was in the same situation except my car was running perfect.
It was base tuned, quick street tune. Doesnt take much boost to do some damage, literally a single aggressive pull without being fully tuned is all it takes

 

so you had boost the whole time?

again we won't really know what the cause is until we find out what is broken, but you can detonate without boost if things are way off.

i can get my NA cars to ping.

 

Pop the exhaust manifold off and move the rotor in question to where the apex seal is visible through the exhaust port.

first visually inspect seach apex seal. Then, press on each apex seal, check and see if you got a sticking apex seal. You should have some springyness to it. If one is stuck try some carb clean and work it with a plastic piece or your fingers

if you have 60 0 0 then 1 apex seal affects 2 chambers.

 

But in my experience the 60psi would be no sideseal ( stuck in rotor slot).

Car will start and run with sideseals stuck in rotor\damaged, but off boost power will suffer.

 

Yea weird you said that cause if i go boost it feels fine lmao . its still apart motors in the car . but it just has a skip to it . so idk i can push in all 3 seals fine with my finger .

 

Are you running meth injection? If you aren't I'd invest into a kit