Single Turbo 7675

[bigriff85]

Mods:
EDP 7675 kit w/ 3.5 inch open downpipe, Ford Racing Aluminator 9.5:1 Compression Ratio, Boss Intake, Mcleod RST kit, Eboost2, ID1000's & KB BAP 93 octane, TSS tune.

At what point theoretically should I take my Boss valve springs that came in the engine out & go to something else like a trick flow? I am making 11psi & around 675rwhp and after 6k the car loses power. I also want to point out that we monitored boost at the manifold (11psi) but my compressor is reading 17psi! 6psi dip from the intercooler seems pretty extreme...also the back pressure was over 2-1 (23psi) we put a bung in the pipe between the up-pipe of the turbo and the merge/y-pipe that connects to the exhaust manifolds.

I know most are going to point out valve float but before I tear into the engine i'd like to address any/all issues with the kit first I find it rather absurd that on low boost like this I'm having this issue but it is what it is. I made almost 700rwhp on this aluminator w/ a 2200 on 13psi and didn't have this issue at all...I know the 2200 loads the engine differently so probably a moot point. Also what springs should I go with? Just the drop in Trick Flows? I'm just looking to make roughly what I am now but I'd like to be able to rev my car at least to 6800 or so and stay around 680-700rwhp. Thanks for any input it's greatly appreciated.

Here's my graph w/ rpm and boost...

 

[corepwn]

The supercharger did not apply pressure to the exhaust valves, which is why you can make 1000rwhp on a stock valve spring blower car but the smaller single turbos create a lot of back pressure in the exhaust and cause the valves to float.

JPC recommends the Trickflow valve springs for this reason. I think anyone selling the 76/75 turbo kits without being upfront that the back pressure will screw you above a certain power level without higher pressure valve springs installed is just misrepresenting their product. The downside is that the valve spring upgrade is a pretty heavy job and will add a lot of cost to these kits if the owner can't do the job themselves, so I can see why it goes unmentioned.

 

[svtlightningx2]

edp turbo

I just went through all this. edp turbo 76\75. aluminator 11.1. valve float on the 9 psi spring netted 7.5 psi boost. went to trick flow stage 1. I can now get 10 psi. anything higher and it shows signs of float. 14 psi it falls flat on its face. Wait for a fix. I think it is because of the 2.5 inch up pipe. Danny is making a 3 inch up pipe and 3.5 down right now. I thought the problem was with the springs but it didn't help much.

 

[bigriff85]

gotcha, I have the 3.5 down pipe on the car now...will see whats up with this up pipe though!

 

[bigriff85]

The supercharger did not apply pressure to the exhaust valves, which is why you can make 1000rwhp on a stock valve spring blower car but the smaller single turbos create a lot of back pressure in the exhaust and cause the valves to float.

JPC recommends the Trickflow valve springs for this reason. I think anyone selling the 76/75 turbo kits without being upfront that the back pressure will screw you above a certain power level without higher pressure valve springs installed is just misrepresenting their product. The downside is that the valve spring upgrade is a pretty heavy job and will add a lot of cost to these kits if the owner can't do the job themselves, so I can see why it goes unmentioned.

i agree 100%. i would have more than likely went another route myself. was told for the low boost and low hp goal i had none of this would be an issue...it's making the power/torque i want and then some...we did a make shift air to water set up from a powerstroke f350 and it made 725/710 w/o changing anything but it still fell off at 6k. that powerstroke intercooler is just wayyy too small for this application but it sure loved the 3 bags of ice being pumped into it for a pull.

 

[svtlightningx2]

dyno graph

whats up with the dyno graph. tq and hp should cross at 5250. and the numbers are off.

 

[bigriff85]

you can't see in the picture but the hp was reading up to 800 so it's a line off.

 

[gimmie11s]

Sucks and sorry to here about this.

Seems every kit has its down side (mine has plenty lol).

 

[wakebum2507]

hmm. i still don't get how mine is so much different, besides the built motor and valve springs. mine didn't see these issues.

 

[Bud]

hmm. i still don't get how mine is so much different, besides the built motor and valve springs. mine didn't see these issues.

What spring and how much co2 are you putting on the gates, to net what manifold pressure?

 

[MRSUPRA]

Nice numbers. 675rhp on 93 is not bad. I wouldn't let the power falling off a little on the top end bother you too much. You're making 400rwhp and full boost at 4K RPM's.
These turbo graphs are never going to look like a peaky centri graph with the centri making full boost at max RPM.

 

[wakebum2507]

What spring and how much co2 are you putting on the gates, to net what manifold pressure?

not using C02, but i'm adding 6lbs on the gates to net 15lbs total, with 9lb springs in the gates.

using the compressor cover as pressure source for the boost controller, and have my charge pipe tapped just before the TB to collect boost data to my MAP sensor.

graphs don't fall off like that.

 

[wakebum2507]

blue lines are on gate, others are leaning on it a bit more.

 

[corepwn]

Nice numbers. 675rhp on 93 is not bad. I wouldn't let the power falling off a little on the top end bother you too much. You're making 400rwhp and full boost at 4K RPM's.
These turbo graphs are never going to look like a peaky centri graph with the centri making full boost at max RPM.

These engines are not meant to peak at 6k, and to use them like that is really handicapping yourself.

 

[MRSUPRA]

These engines are not meant to peak at 6k, and to use them like that is really handicapping yourself.

I understand what you are saying: The Coyote likes to rev, and it shouldn't be falling off at 6K. But I guarantee you that this car will be fast with all that low end torque that a centri doesn't have.

 

[Fabbed5.0]

not using C02, but i'm adding 6lbs on the gates to net 15lbs total, with 9lb springs in the gates.

using the compressor cover as pressure source for the boost controller, and have my charge pipe tapped just before the TB to collect boost data to my MAP sensor.

graphs don't fall off like that. View attachment 50029

your boost controller is masking the issue. Put it on straight wastegate spring and watch what it does.

 

[wakebum2507]

blue line is on gate only.

are you suggesting disconnecting the BC all together and trying it?

 

[slow306stang]

But I guarantee you that this car will be fast with all that low end torque that a centri doesn't have.

My centri makes 450wtq at 3000rpm and 650wtq at 5000rpm on 10psi

 

[wakebum2507]

another EDP car.

 

[Fabbed5.0]

blue line is on gate only.

are you suggesting disconnecting the BC all together and trying it?

Yes

Get it on a dynojet where software cannot be a factor.