Has anyone tried .06 larger exhaust valves vs. the 1.77 intakes? I'm thinking that the intake volume can be increased by adding boost/fuel but the exhaust side is still only being forced out by the piston(with alot more boosted volume to get out!)I think that this may help reduce the boost backpressure and heat through the engines cycle because more volume will be going out the exhaust and not trying to go back up the intake during the overlap period letting the turbo work easier.Manley only makes the 1.77/1.50 and Ferrea is suppose to be getting a quote for 1.71/1.56.They said it would be expensive but then again what isn't.Is this a good idea or bad?
Read the current issue of GM High Tech Performance. The Sept./Oct. issue just hit my mailbox. It has an excellent article on valve sizes on the Buick Turbo head. (Especially the exhaust side!) You are on the right track. There is a cheaper way to go rather than the Ferrea.
Also make sure you read the article about the LS1 V10. I was part of that program while I was with GM.
Donald I looked for GM High Tech Performance at a half dozen stores last night without any luck. Then I looked it up online. It seems like they cover the GN's quite a bit. I think I'll subscribe. You mentioned a cheaper way to go than Ferrea.Does GM have a stock 1.56 or a 1.6 exhaust valve for another application that could be ground down to work in the Buick heads?I think the larger exhaust valves may also help me with spool-up time.
According to the article on page 29, GMHTP says a stock 1.500" exh. valve with a 25* back cut flows the same as a Ferrea up to .500" lift. They say the GM SS valve is good for all but a full race motor. (And its one heck of a lot cheaper.) You want to port match and polish the exh. port only. You only go to Ferrea exhausts if you have a solid roller cammed race motor.
The GM intake valve, on the other hand, is junk and they recommend the Ferrea 1.775" with an undercut and a mild bowl job.
GMHTP is a great mag with a fairly sophisticated readership. There is a GN/T Type article every issue. Last year, they did an all Turbo Buick issue. Purchase a back copy. You will enjoy it.
Thank You Donald for your help!!I appreciate it!That is probably the path I will take. I found GM High Tech at Barns and Noble. Online they had parts 1&2 of Jack Merkel's 3.8 buildup and I think I will get the back issue "all Buick" magazine.
I will read the LS1 V10 article.Just glancing at it it looks like a beast.Put a turbo on it and put it in a Buick and this Web Site would have 2000hp street cars on pump gas!