Same MPH at the track with any boost level?

[neat]

Here's the scoop on my Regal. It's stock with the exception of a straight pipe in place of the cat, a walbro fuel pump, adjustable WG rod, and a Kenne Bell chip from the late 80's. With 100 octane gas, I was able to run 19-20 PSI, and manage a few 13.6's @ 98 at the local track.

I recently added an RJC power plate and an RJC boost controller. Yesterday, I went to a different track, that is notoriously faster than my home track. I pulled into the pits and pumped all the pump gas out of the tank using the fuel pressure port on the fuel rail. I then added 10 gallons of 100 octane. I had set the boost controller at 14-15 PSI for the 100 mile drive to the track because I was using pump 93 for the drive down. I figured I'd make one or 2 passes on 14-15 PSI, just to be sure all the 93 pump was out of the system. My first pass was a 13.6 @ 98. I was stoked, I had just equaled my best run ever, on nearly 5 PSI less boost! This must be a fast track!

I returned to the pits, and tightened the boost controller 2 turns, which put me at about 17-18 PSI. I then ran a 14.1 @ 98. My audible knock was silent the entire time, and I thought it was a good run. There was no MPH increase though. An ET loss is no big deal, the launch can F' up an ET, but I thought for sure the MPH would of come up. I tightened the boost controller another 1/2 turn or so, and made another pass. I got some audible knock at the top of second so I let out of it. I turned the boost back down and made some more passes.

I made probably a dozen passes at 17 PSI, and was never able to increase the MPH from the 14 PSI pass, or reduce the ET any. Anyone have a guess why the extra boost isn't helping me go any faster?

The other thing that concerns me is the detonation at 18 PSI. I went to 20 with the adjustable waste gate rod with no problems, no detonation at all. Now I have an RJC power plate, and and RJC boost controller and I can't seem to go past 18?

I thought the chip might be the problem, it is an ancient Kenne Bell, so I tired a Thrasher chip that a buddy had. With the Thrasher, I would get even more knock than with the Kenne Bell.

Any idea's?

 

[Royal-T-Ltd]

maybe weak valve springs and/or the need for an aftermarket exhaust/DP the oem is pretty small and your trying to cram more air through it....

OH yeah also what chip are you running ?

 

[neat]

I have three chips:

The stocker, the Kenne Bell, and the Thrasher. The KB is in the car right now becuase it has allowed me to run the most boost without detonation.

The valve springs are the stockers, and have 123K on them right now. I hadn't considered the downpipe, maybe I'll look into an aftermarket one.

 

[Paul Clark]

Do the valve springs.
Big difference.

 

[Adam Connell]

What are good upgraded replacements for the stock springs and where is a good place to get them?

 

[jamier]

valve springs and stuff

bought mine through full throttle havn't installed them yet but soon will, Another thing to look into is injectors there's alot of used 42.5 and 50 lb ers on the board, I'd swap them and install an adjustable fuel pressure regulator before playing with the boost again, give the engine the fuel it wants / needs and the et/mph will come easily alos hotwire the fuelpump the kit is about 35 dollars hope this helps..

 

[neat]

I don't think the upgraded springs are a great idea on the flat tappet cam, the extra spring pressure might wipe out a cam lobe. I would think some stock replacements would be the way to go.

I have some valve springs in my garage from my 1991 Corvette. The specs are basically identical to the stock Buick springs, but the Corvette springs only have about 70k on them though, so they are half as used as the springs on the Buick. I though about swapping them over, but if I can get new springs for $100 or so, I don't know that it would be worth it to use the freebies in my garage.

Thoughts?

 

[Ormand]

I don't think the upgraded springs are a great idea on the flat tappet cam

New springs, and upgraded springs, are two different animals. The idea is to have springs about like the original springs were when they were new. That's only about 80-100 lbs on the seat, and shouldn't be enough to hurt the cam. The OEM springs lose tension over the years, and the engine will not rev past some "magic" number, like maybe 4500 rpm. New springs will get you past 5,000.

 

[Blazer406]

Get you a turbotweak chip too.... you won't regret it.

You have a scanmaster... or DirectScan...?

You really need one of these to begin tuning your car.

 

[mikestertwo]

As advised above, replace the springs with stock replacements and get a TurboTweak chip. I did and love it!

 

[turbot2496]

Are you running a street chip or a race chip? What amount of boost and octane is your chip settup for. You need to find these things out and settup the car accordingly. If the chips fueling is settup for say 16psi of boost, it usually won't go that much faster with more boost and will eventually lean out.

Valve springs is probably not a bad ideal with that many miles but you won't need that downpipe for awhile.

 

[cool 84]

If you find out the cause I would like to know. My dad's t-type goes 108mph at 15psi and at 22psi. MPH never changes and it has a fairly new motor with good valvesprings.

 

[neat]

Are you running a street chip or a race chip? What amount of boost and octane is your chip settup for. You need to find these things out and settup the car accordingly. If the chips fueling is settup for say 16psi of boost, it usually won't go that much faster with more boost and will eventually lean out.

Valve springs is probably not a bad ideal with that many miles but you won't need that downpipe for awhile.

The chip is an ancient Kenne Bell chip from 1988, I doubt it's set up for anything special.

So the consensus is a chip and valve springs. Off to the classifieds I go.

 

[Sweet6]

I would think about a new chip and injectors. You can pick up some good 43 or 50s with chips pretty chip. If the injectors on the car are not flowing well, they are going to cause detonation.

 

[turbo nasty]

Comp Cams 979 valve springs and a Turbo Tweak chip

 

[VadersV6]

Dont let anyone scare you out of valvesprings. Lobes wipe because people are running the oils that are NOT flat tappet friendly. These oils that have the starburst symbol have had zinc and phoshpates drastically reduced over the past few years for emissions reasons. Oils that are friendly for our motors would be the Quaker state "Q" line of oils, Royal Purple, Redline, Valvoline SYN, etc. If you want far better protection, add half a bottle of valvoline SYN oil treatment (they have an oil AND a treatment). This stuff is better than GM EOS. The springs are going to make a huge difference. Get some calipers and measure the installed valve height (spring seat to the underside of the retainer). Write that down and go to a good machine shop. Tell them what you have and what your installed valve height is. They can go through their stock of springs and find whats right for you. They can play with shims and springs on the spot with their valve spring tester and tell you in the end what to go with. I would shoot for about 90 pounds on the seat and about 230 open. I would also recommend going with a new timing chain. Between the retarded cam timing and the bad springs, you're probably down an easy 40-50hp.

 

[Brer Rabbit]

Might be a simple problem...

Get a friend to get in the car with the engine off and tell him to put the gas pedal all the way down and hold it. As he keeps it down u need to grab the throttle linkage and see if ur getting wide open throttle. Im willing to bet ur not getting wide open throttle. My buddy had the same thing happen to him but his car was a carbed small block.