HD manifold test

[M.D.]

Hi I'm just looking for something and can't seem to find it anywhere.

I've been having issues with valve float on my SR. At high boost levels. (Anything above a bar) and past 6k.

It only does this past these levels. I've read a few people with this issues. But I've also read people with 450bhp on stock un opened engines. And I'm struggling to see what's not working with my set up.

I've actually tried it on 3 engines now and it's the same issue. The only common denominator is the exhaust manifold.

It's a top mount td05 style manifold. Now we know it's a good flowing design and it's made well with a good collector and tube runs. But something's not agreeing with the SR.

Now this brings me to the question. Many years ago i remember a test hawsham developments did with manifolds and they found that some apex manifolds caused valve float! As strange as that may be Id like to have a look at the designs that did and didn't work, as Ive got turbo technics to make me a standard fitment low mount exhaust housing for my td05 hybrid so I can run a stock style set up as im not really pushing more than a low mount can deal with anyway.

If anyone knows any info that would be great.

[-ghost-]

Soothe manifold has too much back pressure?

Would stiff springs work?

[sideways14a]

Stock springs are shit, get decent upgraded items in there and it will be far better.

[Actual_Ben_Taylor]

I remember the test you're talking about.

It was the Apex type 2 that was notoriously bad...

[ANDY black s13]

I remember the test you're talking about.

It was the Apex type 2 that was notoriously bad...

Agreed it was the Apex type 2 with the long runner's and equal length of the runners so it looses the pulse effect of the stock unequal length manifold
and as mentioned the stock SR valve springs are very soft like Parker pen springs

[R3K1355]

Could you fit an exhaust manifold pressure gauge in to see if it's creating excess pressure??

[M.D.]

That was one mention but I wasn't sure how to do it without melting the gauge. Or pipe to the gauge.

I've heard about the springs being weak. And if I have to I'll pull the engine apart again and put better springs in.
But the issue I have is that so many people get better power than I have from them. Before getting this issue. Polo was one of them.
I mean it's already a forged build. But with a stock head.

[sideways14a]

What power are you seeing?
Imho anything past 380 and it should have a top end poke, cams, springs, retainers ect.

[R3K1355]

That was one mention but I wasn't sure how to do it without melting the gauge. Or pipe to the gauge.

It's done all the time with Diesels, then run spastic levels of boost and run quite high EGT's.

Any decent diesel forum should have a sticky, guide or something about the proper method of installing a pressure gauge.
or a decent diesel tuner should be able to fit on for you???

[M.D.]

Im currently running 360 but we had to tail the boost off quick as if I held 1.3 bar to the redline the power just died and it sounds like the engine is fouling up. It's a noticeable change too.
I just don't understand why people are able to get 400-450 on completely unopened SRs. Yet I can't get anywhere near that without fancy boost curve mapping with the ECu which is definitely not something people do. And it makes for s horrid engine output as it's mega peaky.

[zeppelin101]

Exhaust housing of the turbo would be your next port of call. 450hp is GT30 with reasonable A/R territory which is going to help keep back pressure in check. Not sure how what you have compares?

[Actual_Ben_Taylor]

Im currently running 360 but we had to tail the boost off quick as if I held 1.3 bar to the redline the power just died and it sounds like the engine is fouling up. It's a noticeable change too.
I just don't understand why people are able to get 400-450 on completely unopened SRs. Yet I can't get anywhere near that without fancy boost curve mapping with the ECu which is definitely not something people do. And it makes for s horrid engine output as it's mega peaky.

450 on an unopened engine is rare, I can't think of a single one.

Just fit a set of springs and live happily ever after.

[M.D.]

It's more common than you may think to be fair Ben.
If you google it there's reports all over the place. Well 430ish.
Paul (polo) was one of them.

The thing is. The engine was a fully rebuilt apt engine. So to take it back apart seems sacrilege haha.

[sideways14a]

I am sure there is one or two rare examples, prob with half decent springs on them from nissan for once..

But in general up in those numbers the top has to come off and the bouncy bits made tougher.

[Chriscooke]

Can't some places swap out the springs without removing the head by pressurising the block keeping the valves shut?

[Actual_Ben_Taylor]

It's more common than you may think to be fair Ben.
If you google it there's reports all over the place. Well 430ish.
Paul (polo) was one of them.

The thing is. The engine was a fully rebuilt apt engine. So to take it back apart seems sacrilege haha.

I only remember Paul making that sort of power on a built motor?

[M.D.]

Nope it was a totally unopened one. He melted a piston after a season of beating. So put a second hand one back in. And away he went. Had nothing more than a steel head gasket.
I've been watching a turbo recently on driftworks that was taken from a totally un opened SR. That made well over 400 too.
All stock cams the lot.

[R3K1355]

Can't some places swap out the springs without removing the head by pressurising the block keeping the valves shut?

Possible if you stuffed something up the exhaust and had a big compressor to keep the air flowing?

[zeppelin101]

Possible if you stuffed something up the exhaust and had a big compressor to keep the air flowing?

Pressurise the cylinder through the spark plug hole, assuming your rings actually seal worth a damn.

[Jezz_S13]

you can feed rope into the cylinder too, then compress it against the valve.
https://www.youtube.com/watch?v=zFmC66YU6zI