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boost dropping ?

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Old 09-26-2007, 12:04 PM
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I havent verified myself as dont really have any easy means of testing.

But this is what the supplier says
The springs we use setup at 135lbs on the seat and 350+lbs open
Parallel dual springs with Ti retainers.

I dont think its a head related problem....unless its my own head !!!!!
Old 09-26-2007, 03:31 PM
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at what height? and did you check with a height mike?
.050" more height can lose up to 30lbs of pressure...
I've just checked and changed my springs.Locks had pulled through .100" and the springs had lost 60lbs of pressure on seat...
Had boost loss at the euros at higher rpm(7000+) and i cured that by reseating the wastegate valves.I now have new better wastegates....
Old 09-26-2007, 04:55 PM
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Havent checked height.

for there to be 50thou difference, that would be very visible in terms of apparent valve recession within the chamber, as 50 thou is a fair bit ( I know its just an example )

All valves were sitting the same within the chambers, all installed heights were pretty close ( not exactly the same, but even new they werent either )
Whilst I havent measured, I dont believe the installed height would have changed any noticeable amount.

No time to worry about it now. I'll look at it all after this weekend, and might even consider a cam change once Ive tried some other rockers.

Im heading to Avon this weekend Andy....despite problems, car does feel pretty good compared to when I was at the Mopar Nats with the 5.7. It is defo making a lot more power now, than it was then. But still unsure if it is any better than when I did my PB last October.

But Im still hopefull....


OK...I just checked seat pressure at a couple of springs. Using a crappy 0-1000psi gauge, springs appear to open at circa 100-110psi. Defo not less than 100 though. Hard to tell exactly as its a crappy gauge.
Its a spring tester I bought from Summit ages ago....dont recall which brand. Bought it for other reasons, hence the 0-1000psi gauge.

On the plug side of things. Here are the 4 plugs from the left side. Right are a pain to get at.
These have maybe 1200 miles on them, with some racing. NGK platinum, heat range 7. ( PFR7B - Ive been using same type since May 06 too )
Removed after a short drive, with some testing.

Strange reddish colour on the procelain on cyl 5 ?? any ideas as to what that might be ?
Electrodes also appear very white. Strangely with this engine EGT's as measured in header tube 7 are circa 1100degF +/- 100degF, which is higher than I recall previously. This temp is when cruising, and normal driving.


Last edited by stevieturbo; 09-26-2007 at 05:41 PM. Reason: update
Old 09-26-2007, 07:50 PM
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That spring pressure sounds VERY low!
A similar build to yours would typically have at least 150psi on the seat
and 400psi over the nose of the cam to ensure good valve control.
My Patriot Extreme Gold springs set up a little over 160 if memory serves???
Your existing spring pressures are a little light even for a N/A build.
A boosted car really needs good springs.
Try a set of good springs if you can get your hands on some before race day.
Nice ride by the way, one of my favorites on this site.
Old 09-26-2007, 09:07 PM
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You need to find someone with a spring tester.

I ran the beehive PSI springs with 20psi and the 222/228 XE cam well over 7000rpm with 130 on the seat and zero issues for a whole season.

It really depends on rockers, valve weight, lifter design and cam profile. Hard to believe the springs just crapped out while swapping engines but stranger things have happened. I would get the springs checked and see where they are at, someone around you has to have a decent spring checker.
Old 09-27-2007, 02:40 AM
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Originally Posted by stevieturbo
Havent checked height.

for there to be 50thou difference, that would be very visible in terms of apparent valve recession within the chamber, as 50 thou is a fair bit ( I know its just an example )

All valves were sitting the same within the chambers, all installed heights were pretty close ( not exactly the same, but even new they werent either )
Whilst I havent measured, I dont believe the installed height would have changed any noticeable amount.

No time to worry about it now. I'll look at it all after this weekend, and might even consider a cam change once Ive tried some other rockers.

Im heading to Avon this weekend Andy....despite problems, car does feel pretty good compared to when I was at the Mopar Nats with the 5.7. It is defo making a lot more power now, than it was then. But still unsure if it is any better than when I did my PB last October.

But Im still hopefull....


OK...I just checked seat pressure at a couple of springs. Using a crappy 0-1000psi gauge, springs appear to open at circa 100-110psi. Defo not less than 100 though. Hard to tell exactly as its a crappy gauge.
Its a spring tester I bought from Summit ages ago....dont recall which brand. Bought it for other reasons, hence the 0-1000psi gauge.

On the plug side of things. Here are the 4 plugs from the left side. Right are a pain to get at.
These have maybe 1200 miles on them, with some racing. NGK platinum, heat range 7. ( PFR7B - Ive been using same type since May 06 too )
Removed after a short drive, with some testing.

Strange reddish colour on the procelain on cyl 5 ?? any ideas as to what that might be ?
Electrodes also appear very white. Strangely with this engine EGT's as measured in header tube 7 are circa 1100degF +/- 100degF, which is higher than I recall previously. This temp is when cruising, and normal driving.

Springs sound low for sure to me.Intake side should be min 130 and 150 preferred because the boost pressure tries to open the valve.
the 3rd from the left plug looks rich on the porcerlain.Just wondering if you're seeing higher ex temps if the timing is retarded more than before? Less timing will decrease boost and heat up the exhaust....Did you check the timing mark at TDC with the engine stripped? Maybe the timing mark is off a few degrees from your other engine?
i use BMW mini supercharged plugs with 4 electrodes.They work really well with the motor on the rich side.Bloody expensive though...
Good luck at the weekend.I'm at the santa pod trying to win S/E....
Let me know how you get on...
Old 09-27-2007, 10:10 AM
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You know this blower stuff goes, it's typically belt slippage or valvetrain issues... of course could be fuel and other issues, but if it's not pulling up top I'd check the obvious big two.

As much as I am huge fan of aftermarket parts, I'd go to stock rockers and check lifter preload.
Old 09-27-2007, 10:27 AM
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Also, if you are shooting meth, I don't know that I would be using those plugs.

Tr6 type plugs would be my choice.

What heads and cam ar eyou running?

Hope you got it licked

Old 09-27-2007, 12:41 PM
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Thanks everyone....

Andy. TDC reference hasnt changed, as this is the same crank as my previous 382ci, and same pulley, which is double pinned. ECU trigger is taken off my front pulley.
I can double check timing though.

I'll get a better spring tester and have a go at that, as well as some stock rockers.
If the springs dont read better with a more suitably calibrated gauge, I'll get some new ones.

As for the plugs....

Surely TR6's would be far too hot ? I have a couple of sets here I could try, but I dont think they would be a good choice. Im almost contemplating a cooler 8 plug at the minute.
Heads are WCCH Edelbrock 215cc, cam is 224/230 0.581/0.591 on 115. So not big by any means.
But aside from the high rpm struggle, I am more than pleased with this setup.
Old 09-27-2007, 01:02 PM
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Originally Posted by stevieturbo
Thanks everyone....

Andy. TDC reference hasnt changed, as this is the same crank as my previous 382ci, and same pulley, which is double pinned. ECU trigger is taken off my front pulley.
I can double check timing though.

I'll get a better spring tester and have a go at that, as well as some stock rockers.
If the springs dont read better with a more suitably calibrated gauge, I'll get some new ones.

As for the plugs....

Surely TR6's would be far too hot ? I have a couple of sets here I could try, but I dont think they would be a good choice. Im almost contemplating a cooler 8 plug at the minute.
Heads are WCCH Edelbrock 215cc, cam is 224/230 0.581/0.591 on 115. So not big by any means.
But aside from the high rpm struggle, I am more than pleased with this setup.
Didn't mean 6's as such, just that style of plug when shooting meth

Try same heat range but in a tr style....I have heard of problems eating plugs, but not the tr's...also probably cheaper

Not saying it will fix your problem, just a side note.

So...how much improvement with belt tension fix?
Old 09-27-2007, 05:07 PM
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new belt has pretty much sorted the boost. It still doesnt want to rev. Anything beyond 6500rpm is a struggle.

Even in lower gears, whilst it would hit 7000rpm easily enough, to take it further, would be like ringing the life out of it. It just doesnt want to be there.

Cant get any TR style plugs in the UK, although I do have some 6's I bought from the US when I started using an LS1. Tapered seat plugs are pretty much non-existent here, as virtually every car uses "gasketed" plugs as you guys call them.
Hence Im using these plugs...Ive used them on plenty of other engines, and never had any issues. Very very good plugs.

Tomorrow night, I head for England....if weather holds up, can run both saturday and sunday.
So hopefully it will hang together for some decent runs.
Old 09-27-2007, 05:16 PM
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It's really the platinums that I have heard some have problems with....when shooting meth

Good luck with it

Last edited by rjw; 09-27-2007 at 05:22 PM.
Old 09-30-2007, 08:07 PM
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F'in car

Just back from my weekend away.

Car felt terrible all weekend ( relatively speaking ). Didnt want to rev, and just lacking power.
Didnt hit 7000rpm all weekend, and was rarely above 6600rpm, in any gear. Boost did seem pretty consistent though. Although on the logs, its doing the same thing this engine ( old and current ) has always done. At 6500rpm there is always a dip in the boost log....just a brief one, but its always there at 6500rpm. Has been for months.

I did eventually manage 10.32 at 142, but that was my highest terminal, which is poor...but I guess expected when the car feels so bad at the upper rpm's

I just hope I can get this damn thing fixed soon. Ive ordered a 0-300psi spring tester from Summit, so hopefully it should be here in a week or so, and I can do a better test on the springs.
Should have a set of stock rockers in a week or 2 as well I hope, and PR's to allow me to try the Jesel's if need be.
So I guess there is still some potential here once my problem is fixed.
Old 09-30-2007, 08:38 PM
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Originally Posted by stevieturbo
F'in car

Just back from my weekend away.

Car felt terrible all weekend ( relatively speaking ). Didnt want to rev, and just lacking power.
Didnt hit 7000rpm all weekend, and was rarely above 6600rpm, in any gear. Boost did seem pretty consistent though. Although on the logs, its doing the same thing this engine ( old and current ) has always done. At 6500rpm there is always a dip in the boost log....just a brief one, but its always there at 6500rpm. Has been for months.

I did eventually manage 10.32 at 142, but that was my highest terminal, which is poor...but I guess expected when the car feels so bad at the upper rpm's

I just hope I can get this damn thing fixed soon. Ive ordered a 0-300psi spring tester from Summit, so hopefully it should be here in a week or so, and I can do a better test on the springs.
Should have a set of stock rockers in a week or 2 as well I hope, and PR's to allow me to try the Jesel's if need be.
So I guess there is still some potential here once my problem is fixed.

You'll get there....just hang in
Old 10-03-2007, 01:08 PM
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SOOOOOOOOOOOOOOOOOOO

I have to say I am impressed with Summit.....valve spring tester arrived a day ago, although I only got it today.

Anyway.

If you were to use a 0-300psi Proform valve spring tester, and it indicated the valve was opening at 100psi.....I guess this would be a cause for concern ?

Damn......but at least I seem to have found a major problem.
Old 10-03-2007, 03:20 PM
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Info coming in drips and drabs I know....

Ive tried to measure the installed height of one of the springs.

Valves are REV CL-1175, and 1169 exhaust valves.

Springs...dual, unkown, Ti retainers, flat.

Measuring as best I can, and I do believe this is accurate. Actual spring length when installed, is 1.89", as measured at one of the exhaust valves. All valves are pretty much level.
Old 10-04-2007, 03:16 PM
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Stevie,what is the pressure of the spring at 1.89"?
Old 10-09-2007, 05:19 AM
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Any update????
Old 10-09-2007, 07:22 AM
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my unexplained power fall off was from actual timing at the crank being far lower than commanded timing (crank reference) when i fixed that i picked up over 150 horse

maybe your exhaust is clogged up? somethin get in there and build a nest while the engine was out?

cant remember what my springs were when tested. but shimming them did not help... as it was an advance problem in my case.

O/T KP where do you get all that voltage from.. dang can i buy some?
Old 10-09-2007, 07:32 AM
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Originally Posted by MIGHTYMOUSE
my unexplained power fall off was from actual timing at the crank being far lower than commanded timing (crank reference) when i fixed that i picked up over 150 horse

maybe your exhaust is clogged up? somethin get in there and build a nest while the engine was out?

cant remember what my springs were when tested. but shimming them did not help... as it was an advance problem in my case.

O/T KP where do you get all that voltage from.. dang can i buy some?
Yea, I am always a little suspect when something just stops working all of a sudden. Not to say that valve float isnt possible, may have had some with the old combo, but it may be more a combination of things then just one.

Friend of mine with a BS3 did the same thing on a turbo car with the advance, went from 99 to 118mph in the 1/8 by puting 10 more degrees of timing in because the car just ran like poop and was trying anything. Just madee a slight error when doing the TDC mark..

Voltblaster, 145amp alternator, 2ga alt cable, 60lb battery and only a 10% underdrive damper. Probably costs me 30hp though


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