GM-HiTech Performance Article

Jerryl

Tall Unvaccinated Chinese Guy
Joined
Dec 14, 2004
I was looking at the magazine rack today and saw the latest GM-HiTech performance. There was an article that dicated how a change to the 62mm turbo had substantial HP increase over the 58mm at 20 psi.

I scanned the aricle and it looked interesting but, I did not get the magazine because it is contrary to some of my understanding.:rolleyes:

Interested in a stimulating some discussion on this to learn.
Anyone see this article?
 
Yeah, I've read the article. Apparently ported heads makes you loose boost that can never be recovered. :confused:
They also seem to just gloss over the fact that a new forged shortblock was installed at the same time.

Just keep throwing parts at it, and tune it with a $8K Snap-On scanner reading off the the painfully slow ALDL and you'll get more horsepower. :rolleyes:
 
Yeah, I think GM High Tech is losing some credibility....first a test of the best "cam only" LS1 grinds, but they happen to throw a FAST intake, 90mm t-body, and rockers at it too. Then they put out this garbage. Why would you test it at 20psi, then add heads, cam, and headers but lower the boost by 3psi?
 
it was more informative to my 5.3 that can be made a 383 an make a ton of power ..... when i put my car together abt 5 yrs ago i was always a step above gm high tech and i knew nothing then
 
Im glad im not the only one who was bothered by that horrible article. They were running a Precision 5857 at like 16psi and claiming it was out of flow/power so they changed turbos. All they had to do was turn the knob on the boost controller
 
..Oh, and a few months back, they had a "Turbocharging 101" article where they went on and on about the compressor side of the turbo, ..only to show a picture of a turbine housing! = retards
 
Yeah, I think GM High Tech is losing some credibility....Why would you test it at 20psi, then add heads, cam, and headers but lower the boost by 3psi?
Well kinda what I was thinking, and I only glazed the article in the store . . . than put the magazine it back on the rack. :D

Yeah, I've read the article. Apparently ported heads makes you loose boost that can never be recovered. :confused:
They also seem to just gloss over the fact that a new forged shortblock was installed at the same time.

Just keep throwing parts at it, and tune it with a $8K Snap-On scanner reading off the the painfully slow ALDL and you'll get more horsepower. :rolleyes:
HAHAHAAA. That is what I got out of it.


Which month is this?
I need to read this for sure...
July . . . . I think

..Oh, and a few months back, they had a "Turbocharging 101" article where they went on and on about the compressor side of the turbo, ..only to show a picture of a turbine housing! = retards
Yeah, I noticed that as well . . but after this article I did this; :rolleyes:
 
Hello,

To answer some of your questions and criticisms...

1) With the ported heads and cam, no matter how much we turned the screw on the boost controller it would not reach 20psi as we had previously. If that is incosistent with some of your previous experience, all I can tell you is that is what happened. This is not at all uncommon with turbo and supercharger applications. Boost pressure is directly related to resistance to flow.

2) The Turbocharging 101 article picture screw-up was a mistake made by our art department (that we should have caught), and we printed a correction/retraction. Our grasp of turbocharging was quite apparent by that entire sequence of articles...some of which may have been too basic for some, but there are plenty of people that don't have the level of knowledge as some of you that have been messing with turbos since the '80s.

3) A forged short-block was not installed with the first turbo, which we found ran out of steam. There was a basic rebuild at that time. The forged short-block was added when we switched to the second turbo from Precision (6262B). That was done by the owner, not really part of the build up, and probably unneccessary. We felt three pictures and an accompanying caption of description was sufficient, in the interest of being completely honest and not short-changing the reader (though as I said it wasn't really part of the build).

3) As for the LS1 cam story...the term "cam-only" is generally accepted in the LS1 community to mean that the cam is the only internal engine modification. All other bolt-ons such as intake manifold, throttle body, exhaust, etc is acceptable. Take a look on LS1Tech at the cam-only records, they all include FAST 90mm and other intake manifolds. The rocker arms were stock.


If you guys have any suggestions of stories you would like to see, please let me know. We are open to doing more advanced tech, and will be in the process of exploring that with our Standing Mile Trans Am as well as other planned builds and stories. Thank you.

Sincerely,

Scott Parker
Editor
GM High-Tech Performance
 
If you check out the first link, you will see that it was corrected before it was uploaded to the website. Feel free to check out the rest of the series, and let me know if there is more information that we left out for a "104."

Basic Turbocharging Components & Theory - GM High-Tech Performance Magazine

Turbo System Fabrication - Turbocharger System Hot Side Build Theory and Application - GM High-Tech Performance Magazine

Turbo System Fabrication - Turbocharger System Cold Side Build Theory and Application - GM High-Tech Performance Magazine
 
Thanks for chiming in Scott. I can tell your proud of the 'SALT' trans am and you should be. Thats a very extreme project for GMHTP (my subscription has been uninterrupted since 01') and Im looking forward to the finished product. But back to this Buick article. What does Precision say about you only being able to make 300-ish WHP with a turbo that they rate for over 600hp? (the 5857)
 
Hello,

To answer some of your questions and criticisms...

1) With the ported heads and cam, no matter how much we turned the screw on the boost controller it would not reach 20psi as we had previously. If that is inconsistent with some of your previous experience, all I can tell you is that is what happened. This is not at all uncommon with turbo and supercharger applications. Boost pressure is directly related to resistance to flow.


Scott Parker
Editor
GM High-Tech Performance

Scott, I do agree with your statement that "boost is restriction", but do not think that the reason you could only produce 20 psi with that turbo is because of ported heads giving more flow. :confused:

I am sorry that I am not familiar with the article, but in dyno and track testing we have found many times problems increasing boost are caused by various things.

Many times we have found defective wastegates to be an issue. The typical gate and actuator found on aftermarket downpipes very often are too weak and will bleed pressure. External gates can have a leaking diaphram or improper spring pressure.

I can only say that in 25 years of building, tuning and driving turbo Buicks, your experience in that article is "uncommon" based upon what you are stating.

This is NOT "bashing" you or your magazine, as I appreciate what has been published over the years. I was an early subscriber, and still have an original "TURBO" hat and "TURBO" license plate!

Since you are a member of our forum, please feel free to ask for input, or and ideas or help to make your job easier. Thanks for being here! :)
 
Yea Scott im not a subscriber but i always buy it on the newstand even when there arent any buick related articles....I appreciate that you still find a place to give our 20+ years old cars some ink!!! As far as tech goes maybe you could do an alky kit install or an e85 conversion...

That or a street vs drag race front and rear suspension setup with typical mods like adjustable shocks,control arms and rear sway bar...so some of us rookies will know how to adjust for street vs set on kill for max hook and E.T

.....Even a brake comparison would be cool..stock,vs s10 conversion ,vs trans am conversion,vs aftermarket stock size rotors with dual piston calipers,vs larger aftermarket setups to see if theres really a difference...

Some restoration articles could be cool like adding stainless brake lines and doing a larger stainless fuel line to add performance at the same time all while looking stock ...

Last but not least you could get with Scott from gns and do a Sequential LED swap do the tails, third brake light,interior,and maybe an added bonus his new led park lamps the prototype are just about done then add an HID headlight kit.... Just a few ideas HTH...
 
Scott,
First off; Kudo’s as stated for keeping these cars in the spotlight. Like many, I enjoy reading the articles.
You are one of the few magazines that gives “real advice”.

Regarding the latest article on the TR;
Two things that raised some eyebrows in the article, were the dyno tuning with a Snap-On tool and the boost issue.
I am confident in stating that 99.999% of the members on this board will agree that for such a very respected magazine, the tuning tool decision can affect magazine/organizational credibility.
As far as the boost issue you faced; We all understand “issues” when you own these cars, but a single clarifying statement could easily negate the perception on inadequacy.

Personally, I would LOVE to see an article on some of the development people have come up with for the Non-IC’d cars. (83-85)
There is a member on this board running low-mid teens, non-intercooled and I think it would be a neat story.

I am still stumped as to the HP increase at the same or slightly increased boost level. :confused:
 
After being brought all the way to New Jersey from Florida with the promise of a story in the magazine and then getting there and being completely ignored by the then editor, I have no use for this rag.
 
Thanks guys for the input and ideas...we will definitely have some more meth injection and E85 stuff upcoming. With this GN we have some suspension work on the horizon. And for those of you into corner carving, we have some cool G-body stuff upcoming as well. We'd be interested in any 83-85, so long as it has EFI.

As for tuning on this project, we are in the process of sorting that out as well as investigating some issues with the internal wastegate. Since this is an adjustable Turbo Tweak chip, the Snap-On tool was used to make adjustments. The wideband O2 is recording the air/fuel, so I fail to see how the speed of the ALDL port would make a difference. The timing was kept so conservative that we didn't have to worry about knock from running too much. In fact, that is one of the things we have to sort out, there is plenty more power left in the tune alone (mostly under the curve).

As for horsepower capabilities of the previous turbo and our issues, we really didn't talk about that with Precision. I told them our issue, and suggested that we upgrade to a larger turbo. And the larger turbo allowed us to run 20+psi again, problem solved. As our ultimate goal was to run faster than the previous turbo would have allowed, we are better off anyways. By the next article we should have all of our issues sorted out, and the car will be running up to its potential.
 
Scott,

As a looooong time reader and subscriber..... i would like to say thanx for keeping us in the magazine as well... AS LONG AS YOU CONTINUE SUPPORTING US [Buick Enthusiasts] I WILL CONTINUE SUBSRCIBING:D:wink:

plus Jim McIlvaine rocks....

My only concern would be some of the tech articles do lack..... Our Tech Advisor [Brian] BISON - as well as Otto Pernek of Otto's Performance would probably make an additional 100-150 HP from some of your combos..... and that is the kind of tech i would like to read about....

aaron
 
Scott,

Thanks for coming over. This proves that someone over there has a grasp of damage control and responds to allegations before they become an issue.

I won't get into too much detail about the described modifications to that car.

I will add this though.

There are battle proven ways to work these cars, all of that information is here. Reinventing the wheel is a choice that GMHT makes. A call to any of the techs here would have put that first turbo in and above the sweet spot as it does not come alive until 20-25 psi.
I realize that the TR community is small and not of a whole lot of interest to most of your readers. In this case (even with your respected techs and their knowledge) having someone from here such as Otto or Bison consult with your techs may be a dime worth spending as far as credibility. I know this probably is not that important to GMHT, but all of the information published should be accurate and reliable for someone looking to spend money on one of these old cars.
 
Thanks guys for the input, this car will come around...mistakes have been made along the way and owned up to. These are the kind of things that happen with homebuilt projects, and now we have some people involved that are going to help get this on track. I just heard today that it sounds like we got the tuning figured out, and will definitely need to get to the track and dyno soon. Sounds like we had an issue with cam sensor timing.
 
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