1fastacvw

i have learned quite a bit from everyone on here so i figured ill throw this out here and see what kind of responses we get.

trying to decide between GT4088r or GT4294r. max hp with my setup will be around 650hp. this is with an intercooler.

engine disc is 140 cubes, or roughly 2300 cc's. max rpm will be 8500. max boost i could run is prob 30 but not for long as a stock case probably wont handle it. im thinking the happy zone for me will be max of 25lbs. i know to make 650 ill have to run upwards of 30+. i will be getting a much better case though next year that will be able to handle the hp.

the GT4088 seems to be the turbo to get but im just curious for other opnions.

also, recommendations on wastegate size too. im planning on getting TiAL 46mm for gt40 and TiAl BOV. but if the consencus is gt42, what would you get?

im going to set it up to take advantage of the divided exh housing to help with spooling by paring up opposing cyl fire order.

ty
dean

boostedcivicsir

normally threads like this will be closed and a direction to the faq's. but this actually has a little bit of thought.

mose will say the 40r or 4088 is too laggy. i think the 4294 may be a large turbo for your goal.

seems that you have your manifold already chosen. i think youll be ok with the 4088. someone else chime in please. im a lowly t3.

TheShodan

iTrader: (14)

I take it that this for an all-drag car?

1fastacvw

yes, drag car ONLY.

its on a vw aircooled engine (horizontally opposed), im going to make the exh as equal length as possible. the intake will be whatever i can fit in. the turbo will be sitting right in middle of motor to make the header as equal length as possible. i feel that is more important for creating an efficient running engine.

I have read about intake runner wave length theory but felt the exhaust pulses would be more important ecspecially when trying to choose between the two. on the intake side though, i calculated out based on air speed to use a 2.25" dia. runner. even if i made the intake design more important then exh, the shortest i could make the runners would be about 14 inches. that would be from the tb back.

i spoke with a person who deals with garret and he told me that garrett under-rates the hp estimates for the turbos? not sure if that is correct statment or not. He told me that on it will make more hp then they show it rated for.

I have done some calculations and the gt40 seems to be the right one but hate to spend the money and end up not being the right one haha.

it willl be about three to four weeks before the motor is finished. i have to do more machine work on crank, cylinders, etc before its completed. i can post pics at that time to give better indication of what where faced with.

Also, another vw racer, he is the fastest sedan to date with sim engine size runs 8.50's all day but his case case can handle the pressures etc. they also put more boost into it 35 lbs im guessing, they ran a 4294r as well. thats primarily the reason why i ask and am checking. gotta keep up with the jones' haha.. (but im still not in thier league, lol )

As a side note, i didnt know if posting this here was legal or not. haha..

ty
dean

TheShodan

iTrader: (14)

The HP that Garrett calculates is based upon a flywheel hp in a general range. It is up to the user to calculate the correct hp rating for their needs BASED upon the data Garrett or Borg-Warner or Holset that was given.