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Discussion in 'Power-Adders' started by avexhype, Nov 9, 2015.
U have the right spark plugs but spark plug gap should be .018-.020 not 0.25.
We swapped in new coil packs and regapped plugs to .021 which is fine for under 10 pounds. It helped but it’s looking like valve float at this point. The pulls are very clean now on 6 pounds at 600whp. This graph was on 8 pounds and she put down 678/540, but breakup came back again.
Definitely valve float. On a single, you must have a VERY solid flowing exhaust side to combat this.
1. What is the turbine wheel size and exahust housing size?
2. what is your exhaust set up after the down pipe?
CPR kits dont have this issue because the BW turbos he supplies with is kits are massive on the hot side....like 83mm turbine and .96 or larger exahust housings. CPR also has a 5" downpipe which helps a ton.
Twin turbos can get away with slightly smaller hot sides and slightly more restrictive cat back exahust, but the problem still will arise.
I was seeing valve float with my twins at 8 psi with the stock cat back in place. I swapped out the stock catback for true 3" mandrel bent exahust into 2 3" straight through mufflers at the rear of the car in stock location and now i can see 14-15 psi with no float.
It’s a 76mm with a 4” bumper exit exhaust, there’s really no restriction. I think it has more to do with it being a 119k mile motor that’s spent the last 50k-ish miles at 7800 rpms with full boltons before I put this kit on.
I think at this point I’m going to dial the boost back to keep it safe for now, order a set of trick flow valve springs, then give it another go in a few months.
76mm is the cold side.
What size is the turbine wheel and housing?
Miles on the motor doesn’t matter.
Proper turbo sizing does.
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Does anyone know if CPR still is a 1+ year wait?
On 3 Performance 2nd Gen 76 / 75 BMF CNC Billet Wheel Turbocharger 1125HP | On3Performance
Valve float is not a common thing with these kits. I only hear about float with ON3 twin kits at 15+ psi.
Interesting... so the turbo is basically a copy of the precision PTE 7675.
That turbo has proven to be restrictive on the coyote platform.
I’d bet a lot of money that a larger hot side will clear your issues right up.
This guy had the same problem as you and same turbo.
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Floating for sure. PAC 1234's. I have electric cut-outs myself. Without them I would be seeing way too much back pressure so keep that in mind and yes the 5 in DP helps quite a bit as stated.
So we all agree it's float, I just don't agree with the reasoning everyone else is giving. There's tons of these ON3 kits with bumper exits running around pushing way more boost than I am, and NONE have a backpressure issue. You can't compare a kit on a Gen 3 Coyote above and claim that's the same issue I'm seeing, it's a totally different setup.
I'm pretty damn sure these are just worn out valvesprings. There's not many people taking 120k mile coyote motors and throwing boost at them after they've spent the last 60k miles well above 7k rpms. I think I'm just stuck having to upgrade valvesprings.
Here's the exact same On3 kit on an identical Gen 1 with way less miles...nice and smooth, and it's on 10 pounds...I can't even push 8.
You appear to have all the answers fella. Not sure why youre even asking questions.... and here you have people who have delt with your problem yet you think you know better.
Good luck to you!
Who was asking questions? I posted a dyno and YOU asked the questions. Am I right or?
Don't go get all upset over a simple disagreement over WHY the float is happening. I appreciate your input and will take it into consideration moving forward.
Its not the Turbo kit that's making them float its the valve springs but at higher boost levels the smaller DP will become an issue.
Boss 302 Valve springs which are only slightly stiffer than stock will begin to float at 12-15 lbs depending on set-up. Thats right from Tim at MPR who is the best in the business.
Ur gonna have to spend some money on some decent valve springs and retainers. Worn out or not they are not up to par unless u wanna make 10 lbs of boost forever.
Valve springs replacement is a big job and usually requires taking the cams out and u will need the valve spring removal tool or u can rent mine for $40 but to do valve springs and put stock fresh ones back in would be a bad idea.
Yes PAC 1234
Yeah we "finished" for now. Car put down 623whp/536wtq before seeing float. That was on 6psi. Car will stay at this level until we can get her in for valve train upgrades.
Thats still decent power.
Last I heard was the dude ghosted some people with their cash. That's FB and Yellowbullet hearsay though.
He took the last batch of suckers and ran away with the money.
Thats terrible. I read that too about CPR... sad.
The valve float issue .. bandaiding the problem is valve springs. Brett doesn't have a huge issue because the hot side of his turbo is huge.
Coyotes flow an extraordinary amount of exhaust air and the hot side of any turbo kit needs to be sized properly. This is well documented.
Coyote single turbo size opinions 1000rwhp
That 7675 turbo is too small on the hot side, but valve springs should take you a ways and buy you a few more psi until you address the real issue (back pressure).
My worthless opinion.. it is easier to swap out the turbo for something along the lines of 76/87 but hey.. if you want to tear into the heads, so be it.
Best option is do both.
I didn't hear that about Dustin at CPR. Guess that makes my Kit worth more now lol cause lord knows its the best single kit out there bar none. Its really an amazingly designed and built kit that's terribly efficient.