4.9L Cadillac Information (Page 9/11)
Will AUG 20, 03:28 PM
Hence why the Allante intake makes 20 more HP on a 4.5 than the TBI intake.

Are the TBI and PFI intakes essentially the same casting but with injector bosses in the PFI intake?

Has anyone actually done before/after dynos on a 4.9 with the PFI intake and Allante intake?

Edit: The TBI 4.5 made 180 HP while the Allante 4.5 made 200, right? The PFI 4.5 still made 180 HP, right?

[This message has been edited by Will (edited 08-21-2020).]

Reborn756 AUG 22, 04:45 PM
Hey guys, update: I finally got all the details worked out for the car, and I should be picking it up September 5th! Finally going to be joining Team Fiero. Going to be an interesting change, going from Team Trans Am to Team Fiero. Looking VERY forward to this though, the Fiero is one of my top 10 dream cars (four of which are pontiacs).

------------------
- Darryl

Raydar AUG 22, 09:54 PM

quote
Originally posted by FieroWannaBe:


Stroke has very little to do with the ability of street engines to "REV" its has everything to do with airflow and camshaft timing, Neither of which this platform is designed for. What will happen, is with an identical top end, the lower displacement engine will achieve peak power and torque at a higher RPM. This has been proven time and time again the dyno.

Wear and tear is a factor, but it's affect on power production, as far as street engines are concerned, is effectively nil.

My point is, there is rarely ever a reason to not go with the maximum displacement possible. it makes reaching the desired power goal much easier, since engine speeds can be lower to achieve the needed airflow for a certain power level, provided you have the top end airflow (read: mass-flow) needed to reach that power level.




If I may jump in here....
I have a 4.9, now, with the Allante intake setup.
I have considered doing a 4.5, simply for the reason that the 4.9 has all of that torque, way down low. Hoping the 4.5 could shift everything up higher. (The 4.9 isn't called a "tractor motor" for no good reason.)
Your statement above makes perfect sense, though. And I believe the 4.x lower end, if balanced properly, is more than up to the task of spinning 6K or better. IF it could be fed enough air.

This premise is further precipitated by the crappy gearing available with most Getrags or F23s. Probably the most popular manual tranny options in use.
Yeah... I get it. The ratios suck for a "tractor motor", but it's still a lot more fun to drive than the automatic.
Seriously... Thanks for your input and information.
Raydar AUG 22, 10:03 PM

quote
Originally posted by Will:

Hence why the Allante intake makes 20 more HP on a 4.5 than the TBI intake.

Are the TBI and PFI intakes essentially the same casting but with injector bosses in the PFI intake?

Has anyone actually done before/after dynos on a 4.9 with the PFI intake and Allante intake?

Edit: The TBI 4.5 made 180 HP while the Allante 4.5 made 200, right? The PFI 4.5 still made 180 HP, right?




Missed this... I don't know of anyone who has made back-to-back measurements on a 4.9 Allante setup.
There is a dyno shop not too far from me. I might have to suck it up and go, if they'll take my car. It "feels" fairly well sorted, although I've never had a "pro" tune done on it. (OTOH, I've seen the results of a few "pro" tunes, that were perpetrated upon unsuspecting users. I can do better. Seriously.)
With that said... They are a Nissan shop - specializing in 350s and 370s - so I'll probably get laughed at.

[This message has been edited by Raydar (edited 08-22-2020).]

FieroWannaBe AUG 23, 12:03 PM

quote
Originally posted by Raydar:

This premise is further precipitated by the crappy gearing available with most Getrags or F23s. Probably the most popular manual tranny options in use.
Yeah... I get it. The ratios suck for a "tractor motor", but it's still a lot more fun to drive than the automatic.



The ratios are terrible for just about any engine combo. They sit somewhere In between a close and wide ratios, with a very high 1st, no matter the transmission choise. Standing starts are the worst. But if you stay out of first the f23 is probably the best option behind this engine in my opinion.



Here is a Thrust chart I made of the 282 vs the F23, with a sample power curve I made up (based off of the two dyno graphs I could find online
sourmash AUG 23, 12:12 PM
Never checked but my trans is probably the 440 from the '88 Eldorado the engine came from. I don't like the shift points all that much for performance. It's ok for normal driving.
FieroWannaBe AUG 23, 01:48 PM

Heres a photo of a carbureted 4.9L (with a 2 barrel) dyno. It belongs to Arns85gt.
It shows a lot better top end the the other dyno I referenced, which was Lous_dias. Not sure what was done to either engine but i believe lou_dias had a allante intake, which has extremely long runners relative the standard TBI manifold, and his tune was pretty rich up top.


Here's a thrust curve with carb'd engine numbers.
lou_dias AUG 24, 04:36 PM

quote
Originally posted by FieroWannaBe:


Heres a photo of a carbureted 4.9L (with a 2 barrel) dyno. It belongs to Arns85gt.
It shows a lot better top end the the other dyno I referenced, which was Lous_dias. Not sure what was done to either engine but i believe lou_dias had a allante intake, which has extremely long runners relative the standard TBI manifold, and his tune was pretty rich up top.


Here's a thrust curve with carb'd engine numbers.



I finally tuned it...


Ended up with 196 rwhp before they made some changes to improve idle and we settled where it is in the video... E85 fuel but heavy wheels.
FieroWannaBe AUG 24, 10:02 PM

quote
Originally posted by lou_dias:

Ended up with 196 rwhp before they made some changes to improve idle and we settled where it is in the video... E85 fuel but heavy wheels.



From the looks of it, if both engines have factory cams, it looks like the Allante intake does shift the peaks down about 1000RPM...
Raydar AUG 25, 09:26 AM

quote
Originally posted by lou_dias:

I finally tuned it...
Ended up with 196 rwhp before they made some changes to improve idle and we settled where it is in the video... E85 fuel but heavy wheels.



Pretty cool! That's actually about what I'd expect from an otherwise stock 4.9/Allante setup.


quote
Originally posted by FieroWannaBe:

From the looks of it, if both engines have factory cams, it looks like the Allante intake does shift the peaks down about 1000RPM...



I actually never thought about that aspect of it (as opposed to absolute peak power and torque) but it does make sense.

[This message has been edited by Raydar (edited 08-25-2020).]