Just thinking out loud :icon_question: , I am curious to know the limitation for the stock TB :icon_eek: ? When can going to a bigger TB and porting the plenum become a very noticeable power increase :icon_twisted: ? With data logs, would it be able to be seen :icon_idea: ?
I am just thinking out loud.... ;)
:icon_question:
Anytime you have forced induction getting a vehicle to inhale and exhale easier with less restriction will yield bigger power gains than an NA engine. To be honest a 3400 top end swap with a 3500 intake and a vortec 4.3 throttlebody would be a nice setup IMHO.
Ken
Quote from: cobracmdr on October 22, 2008, 06:07:41 AM
Anytime you have forced induction getting a vehicle to inhale and exhale easier with less restriction will yield bigger power gains than an NA engine. To be honest a 3400 top end swap with a 3500 intake and a vortec 4.3 throttlebody would be a nice setup IMHO.
Ken
We all know the 35 and 3900 swap would be best for flowing needs, but I really prefer to keep the 3.1 until 100% support is no longer available for it.
I am just looking to see when the TB swap really could be a big improvement for power reasons. There has to be a point to when the TB cannot flow enough and upgrading to a few more mm's bigger could yield 20+ hp. Granted the plenum would be port matched to the TB no matter what. Or is the current TB at it's max flow for the actual intake runners ports and upgrading the TB (with porting the TB neck) would not be worth the effort. It would not be worth $200 and 10 hours of custom fab to see 10 to nil results.
The best up grade for the $$$ is a custom down pipe and exhaust kit. There is no point in pushing more air into the motor if you can't get it out.. The stock downpipe and 2.25 od exhaust suck azzz ;) just my 2 cents tho...
I am just wondering what it takes to make the stock tb a real concern. example; you can use a soda pop straw for soda, you can also use it for a milk shake. It wouldn't be a wise idea to do that, but you can if you had to, but upgrading to a proper straw would be easier on your part.
That is what I am sorta asking. I know by doing certain mods/upgrades it would be just the norm to follow suite, but if you wanted to know a cfm or hp restriction when you see it, when would that be with the stock TB?
Anyone ever do a test on this? lol
I just use 2 straws.. :dunno:
:laugh:
I know what you are getting at, you want to know at what point is your TB the limiting factor for making power and that is a complicated answer and I doubt anyone other than a GM engineer has done any extensive analysis of the Gen II TB to determine what it flows as compared to a stock manifold set/head set. I know this from a swag point of view exhaust like Flybynite said is a major area for improvement on a turbocharged vehicle. From reading corky bell's maximum boost multiple times and reading literature sent to me by Adam it is readily apparent that the BIGGER the pressure drop you can get across the turbine wheel the easier it will be for the turbo to spool up thus attaining high power levels earlier in the RPM range. This basically will make your car faster. Now obviously once you get the exhaust uncorked according to your local emissions control laws of course ;) Then getting air into the engine with the least amount of restriction will be another area of improvement. You can always get improvements from making the TB larger but to find out is it holding your back via some engineering flow calculation is going to be more work than it is worth IMHO. It is holding you back, but the level of improvement you will get will vary based on your mods and what was said above.
Ken
Doesn't Kuntzie have that monster 60mm TB? Or something of that spec? Maybe you should ask him what he thinks about it.
I might spend this winter altering TB's and honing a plenum to match. If I do actually find the time to do this, I will try to dyno before and after with no changes to my current modifications. If I see some large gains, then we will know what it takes with certain mods.
Just a fyi, my exhaust is already 3" all the way back.
Quote from: TGed on October 25, 2008, 01:32:39 AM
Just a fyi, my exhaust is already 3" all the way back.
Does this include Downpipe?
From the turbo back.
If I had to guess, I would say the stock tb will flow around 450cfm and the 60mm style will flow around 600 cfm... :icon_mrgreen:
About 191cfm at 27in of watter on a flowbench. Its only 52mm. 59mm flows about 198cfm. Not much gain but a gain. Consider that your intercooler pipes also act like restrictors. No sense in upping the TB size if your keeping the same pipe size and IC. You'll get more throttle response with the larger unit though but thats it.
Think I may try and adapt my spare GTP TB (69MM) to the 3500 upper intake I have for my motor. This will be in addition to installing a 3.4 radiator / dual fan set up, & FMIC. :icon_cool: My charge pipes will be 2.75in (68MM)
Quote from: GPChief on October 29, 2008, 07:29:39 AM
Think I may try and adapt my spare GTP TB (69MM) to the 3500 upper intake I have for my motor. This will be in addition to installing a 3.4 radiator / dual fan set up, & FMIC. :icon_cool: My charge pipes will be 2.75in (68MM)
The 3.4 radiator is going to take up more room IIRC. I think the 1 3/8'' thick radiator in my '93 GP is the same length as the ac condenser. I think it would be better to keep the stock radiator, add a smaller ac condenser, and route the intercooler tubing though where the the stock intercooler sits now(using a same side entry + exit FMIC).
The 3.4 radiator will bolt right in and it will fill the enitire space of the old Rad & IC. Its hard to describe with out pictures. I'll take some when I do this mod.