TB question & thoughts: no BS answer
Thread Starter
Senior Member
Joined: Nov 2000
Posts: 762
Likes: 1
From: down by the river
TB question & thoughts: no BS answer
this is more of a babbling rant but bare with me.
I am running the set-up in sig and have been agonizing over 1. 1.6 roller rockers and 2. a larger TB.
The car runs absolutely awesome and the tune is just about as perfect as I have ever seen them get. It is spot on. Tuning this thing for 2 stages of nitrous as well as a motor tune is really hard and I think I'm just too lazy to spend the countless hours to get it right again. These last 2 mods would make the car "done." I recently came back from the 2 hardest things I've ever done in my life back to back (Ranger School and a deployment) so I'm on "slow mode" right now. Currently I have the stock TB and stock 1.5's on it. I feel as if I can gain quite a bit of starving HP if I do both these mods. Keep in mind this is a 383.
So, should I leave it alone(aint broke, dont fix), just throw on 1.5 rollers and not have to mess with the tune (and gain a few HP anyway), or do both and start all over again.
Also, I see info that puts the stock 48 mm TB flowing about 700+ cfm?? Any belivers.....is it sufficient. Not to mention, the K&N cone I have on the TB is rated at a measily 600cfm, so I guess I would need the 1K cfm filter also (which only fits the larger TB's)
what to do, what to do...where is the real choke point???
I am running the set-up in sig and have been agonizing over 1. 1.6 roller rockers and 2. a larger TB.
The car runs absolutely awesome and the tune is just about as perfect as I have ever seen them get. It is spot on. Tuning this thing for 2 stages of nitrous as well as a motor tune is really hard and I think I'm just too lazy to spend the countless hours to get it right again. These last 2 mods would make the car "done." I recently came back from the 2 hardest things I've ever done in my life back to back (Ranger School and a deployment) so I'm on "slow mode" right now. Currently I have the stock TB and stock 1.5's on it. I feel as if I can gain quite a bit of starving HP if I do both these mods. Keep in mind this is a 383.
So, should I leave it alone(aint broke, dont fix), just throw on 1.5 rollers and not have to mess with the tune (and gain a few HP anyway), or do both and start all over again.
Also, I see info that puts the stock 48 mm TB flowing about 700+ cfm?? Any belivers.....is it sufficient. Not to mention, the K&N cone I have on the TB is rated at a measily 600cfm, so I guess I would need the 1K cfm filter also (which only fits the larger TB's)
what to do, what to do...where is the real choke point???
Moderator
Joined: Jan 2000
Posts: 19,653
Likes: 309
With the heads, base, and runners (plus a cam that can support it) your's may be one of those cases where a larger TB will show real benefit.
The rockers are a crap-shoot. Not knowing the flow characteristics of the heads, how they react to the rest of the induction and exhaust, and the extra oxygen, changing the cam profile may be good, or may be bad. More isn't always better.
The rockers are a crap-shoot. Not knowing the flow characteristics of the heads, how they react to the rest of the induction and exhaust, and the extra oxygen, changing the cam profile may be good, or may be bad. More isn't always better.
Supreme Member
iTrader: (2)
Joined: Feb 2006
Posts: 1,547
Likes: 0
From: 39.84N 105.11W
Car: '89 Trans Am GTA
Engine: WAS 350 - now L92 (alum. 378/6.2L)
Transmission: WAS 700R4, now a built T56
Axle/Gears: 3.27 9-bolt
I'd tend to agree - and, with the 1.6 rockers, I've heard of instances where you have interference with the pushrods:
(That's taken from an article describing an engine fairly similar to yours, exc. this one's running a carb...)
Personally, I've decided to get all of my lift from the cam itself, but YMMV. The larger TB may be of benefit to you (like Vader said), but one thing I'd suggest is to ditch the air filter on the TB, & duct some COLD air into your engine - you're probably moving enough air that you'd notice the difference!
This is what the stock pushrods looked like after last month’s test with the 1.6 rocker arms and the Hot cam. The 1.6 rockers position the pushrod cup closer inboard, which scuffed about half of the pushrods on the cylinder head. You must slightly machine the pushrod holes to prevent this interference.
Personally, I've decided to get all of my lift from the cam itself, but YMMV. The larger TB may be of benefit to you (like Vader said), but one thing I'd suggest is to ditch the air filter on the TB, & duct some COLD air into your engine - you're probably moving enough air that you'd notice the difference!
Thread Starter
Senior Member
Joined: Nov 2000
Posts: 762
Likes: 1
From: down by the river
i cant remeber flow #'s exactly, but i KNOW they flowed better than the Edelbrock E-Tec heads w/ the 200cc runners(this was 2+ yrs ago). I ported my runners out to about 185-190cc and was happy to see i beat the E-TEC 200's numbers. However in the .500-.600 range the E-TEC's might have beat me about by 1-3 cfm depending on the individual runner.
That being said, i was thinking of just going with the stock ratio rockers...but full rollers..........i dunno.
I haven't seen a CAI set-up I like, but maybe i havent looked hard enough. But my 2nd stage is all plummed up into the current set-up so Im not so anxious to re-do all that crap either LOL I'm a loser!!! haha
anything?????
That being said, i was thinking of just going with the stock ratio rockers...but full rollers..........i dunno.
I haven't seen a CAI set-up I like, but maybe i havent looked hard enough. But my 2nd stage is all plummed up into the current set-up so Im not so anxious to re-do all that crap either LOL I'm a loser!!! haha
anything?????
Thread
Thread Starter
Forum
Replies
Last Post