I aleady Have 2 3800sc cars. I want MORE "Bottom end" . the way I see it, it is either change the final drive gear ratio in the trans 4t65e from 2.93 to like 3.73. OR change to a 8 cyl 4.9 Caddy. I'm not spending over $1000 on adapters for a sb chevy. the trans is already there and brand new, so all I would need is a front mount, exhaust, and wires/ecm. the 3800SC is not a "bottom end torque engine", so.... What are the Pros / cons ??? Thanks
One of my performance cars (Grand Prix GXP) has a 4t65e-hd, the other (the Fiero GT) has a 440t4. Your version of the 4t65 may have more differential options, but the hd version only has one. On it to change the final drive ratio I would change the drive gear and chain set. Options are overdrive set (37 drive 33 driven for 2.93 to 1 final drive), one to one drive (35 drive 35 driven for 3.29 to 1 final drive) or underdrive (33 drive 37 driven for 3.69 to one final drive). The actual ratio of the differential in the hd is 3.29 to one.
I am pretty sure the non HD version has a couple more differentials available though...
BTW, one of the best ways to "wake up" a performance car is to give it performance gear ratios IMHO!!!
Still, if deciding between a gearset and a 4.9 caddy engine, my vote is BOTH!
EDIT: I have owned a 3800 v6, but not the SC version. My understanding is it is pretty torquey too, but even it could benefit from a performance final drive ratio...
[This message has been edited by bjm362 (edited 10-13-2018).]
How will you control the 4T65EHD transmission and the 4.9 engine?
olejoedad, you always make good points IMHO! If he is carbureting it there are TPS kits for carburetors. If he is using the TPI system, isn't his PCM already compatible?
Wow are you missing out. Smaller pully gives you more boost, and way more bottom end tq.
Cams can move the tq up, but a smaller pulley with the right mods can mitigate that. With a 3.0 pulley, intercooler, 60lb injectors and a tune I could step the back end out at will with the throttle. Mind you I had the 84 Muncie with the low gear final drive but its impressive. I think I was putting 358 ft/lbs of tq to the wheels on that setup. That was stock manifolds/crossover with a pretty terrible 2.5" exhaust, and super restrictive intake using the factory air box.
I always felt the car was slow with a factory 3800SC in it, but once I did those basic mods it was so much better!
I was going to do the gear upgrade, but sold the fiero. I have the 3.69 gear set I bought (37/33- correction 33/37), if it is of interest to you. I'll let it go for $60 shipped.
Just to advise if you decide the change the FDR gearing of the 4T60e it is a tedious task to change the gears and sprockets. The side cover the valve body, oil pump shaft and rt drive shaft must all be carefully removed. There are 4 steel balls that are in the valve body that will fall out and must be put back exactly in the slots that they were before. The job requires careful re-assembly. IMO, this is a job best left to someone who regularly works on transmissions and I would not attempt it while the trans is in the car.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
I was going to do the gear upgrade, but sold the fiero. I have the 3.69 gear set I bought (37/33), if it is of interest to you. I'll let it go for $60 shipped.
darbysan , the 37/33 gearset is the 2.93 to 1. The 33/37 is for 3.69 to one. If you have the 33/37, and it has not sold already I will buy it for $60.00!
darbysan , the 37/33 gearset is the 2.93 to 1. The 33/37 is for 3.69 to one. If you have the 33/37, and it has not sold already I will buy it for $60.00!
My bad- I typed without looking. The gears are the correct ones for 3.69- I corrected my original post. You are now first in line, if a pending sale does not go through. Will keep you posted.
I aleady Have 2 3800sc cars. I want MORE "Bottom end" . the way I see it, it is either change the final drive gear ratio in the trans 4t65e from 2.93 to like 3.73. OR change to a 8 cyl 4.9 Caddy. I'm not spending over $1000 on adapters for a sb chevy. the trans is already there and brand new, so all I would need is a front mount, exhaust, and wires/ecm. the 3800SC is not a "bottom end torque engine", so.... What are the Pros / cons ??? Thanks
First of all, specifically what does more bottom end mean? You want a bigger azz...lol? If it is torque your after then that is so easy a caveman can do it with the 3800SC. IMHO, it would be silly to swap from a 3800SC to a 4.9 for torque. If it were for the sound I can 100% understand. The aftermarket HP for the 4.9 is almost non-existent? The aftermarket for the 3800SC is huge. Usually us 3800SC guys have way too much torque and can't keep traction with 25% throttle. I'm not sure what research you have done but you will be hard pressed to reliably get more torque potential with the 4.9. Just get some basic upgrades to your 3800SC to support a 3.0 pulley and you are there. I wouldn't touch the trans if I were you but if I did I would go with a 3K stall as that will probably get you what you think you want.
nosrac What makes the 4.9 unreliable when you build it for more torque? John
The 4.9L engine already makes 275ft lbs of torque and the curve is pretty flat from 1000 RPM up. Its a great engine for what it does but it doesn't take well to mods. About the only performance part available is a Delta cam and that will put more pressure on the aluminum rocker saddles possibly breaking them over time. With the right gearing in a Fiero these engines make the car pretty fast.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Hey Dennis, I have heard about the rocker arm saddle failure, but have never seen it myself. Curious. The stock rocker arm hold down bolts only go through about 3/4 of the way in to the rocker arm saddle. I tap the saddle all the way and use new rocker arm bolts that extend 5mm past the bottom of the saddle. I run a high lift cam, heavy duty valve springs, roller rockers, run my motor past 6,000 rpm and have never had a problem with these bolts or aluminum saddles. Just my results from the engines I have built. John
4.9L huge torque monster to begin with. 4.5L short stroke = more rev potential. Think 327 VS 350 sm block Chevy. Most 4.9 owners want more revs. Use the newest block available. 1991 or newer for best oiling, and strength. (more block ribbing) Use the 1990 4.5 rods (longer) for the best rod to stoke ratio with the 4.9 Pistons (better design) (for building the ?best? motor for a lightweight Fiero (4.5L). Use the newest heads - better design. Use either Allante rocker supports - or simply drill and place threaded flanged inserts bottom side up to keep the aluminum threads from pulling. SM block Chevy roller rockers( get 1.7 ratio ones). Bee hive valve springs with SS valves (LS motors). Stud the block - both mains and head bolts. Then make an 1/8" plate main girdle, for even more support. The bottom of the block is flat. Just lay it out using the pan gasket with arms covering the mains. Polish everything - free labor only. Easiest Fuel inject is a 305 out of an F body. Easily hacked and modified. Even has a knock sensor. Fly cut the intake manifold and use a 3.8L Gen 3 or higher Super Charger then smaller pulley to spin it faster. Simple port and polish on the heads. Who says you can't hot rod a 4.X Caddy motor??? ADD: Use factory 4.5L factory headers. Use a Longitudinal 4.1 for a free front motor mount. Weld or bolt an Piece of heavy angle to the frame with a urethane biscuit in between to attach the 4.1 front mount.
[This message has been edited by Mark A. Klein (edited 10-19-2018).]
Okay, so I've been reading along and curiosity is getting the best of me. Mark....so if you do all that modding to the 4.9 as you just outlined just what kind of horsepower/torque are you seeing? And getting back to the 3800 SC for a minute. If you go from the 2.93 to the 3.73 rear gears what's that worth in either 0 to 60 or say 1/4 mile times?
Back to MY "original Question". what size PULLEY is on the 1999 3800SC ? If I go to a smaller diameter pulley, What OTHER Changes Need to be made ??? Thanks
The stock pulley IIRC is 3.7". Dropping to a 3.4" will require a retune.
Dropping pulley size more will require supporting mods.
The 4.9 makes more torque off idle than a stock 3800SC does at full song, even with a bunch of mods the 3800SC needs to make some rpm to get big torque.
*Dropping pulley size more will require "supporting mods".*
"WHAT" supporting mods? what mods to go from stock 3.7 to 3.4..., . to 3.2,... and how much low end will I be gaining for $$$ Spent ????? any HARMFUL side effects ? require race fuel ? is the EGR "bothering anything? need to be REWIRED AGAIN ? all this "detrimental" to a 100K motor ??
As I said earlier in the thread you can run a 3.0" pulley with literally just an intercooler, bigger injectors and a tune. Nothing else required. All other mods on tap of that help unleash the potential of the smaller pulley. With more mods you can go to an even smaller pully.
No race gas required just standard premium gas. This is assuming you didn't put a ridiculously restrictive exhaust on the engine in the Fiero. In a grand prix you would probably want at least a downpipe for the same mods.
The dyno results are about 258 HP and almost 300 ft/lbs of torque at the wheels. This should give you an idea as to what is possible with limited mods.
For more extensive mods, I also have a much modified 3800 SC Series III mated to a Getrag 282 that shows near 300 HP and 300 ft/lbs of torque at the wheels. The following is a list of mods associated with this engine (IIRC):
Northstar TV Tog Headers Large intake Large exhaust ZZP Stage II Intercooler ZZP fuel rails VS cam 85 mm SLP MAF Conservative custom tune
I wish that I had a 4.9 for a direct comparison, but the closest that I can come is a stroked 383 V8 with fuel injection. It has not been tuned as of this date, but the initial dyno run showed around 400 ft/lbs of torque and maybe around 300 HP. I would expect the HP to go up with a decent tune but I have a lot more work to do on this project car prior to tuning it properly.
Back to MY "original Question". what size PULLEY is on the 1999 3800SC ? If I go to a smaller diameter pulley, What OTHER Changes Need to be made ??? Thanks
When you downsize the Eaton Supercharger pulley on the 3800SC series II engine to 3.4" you should use colder plugs a 180* stat and a larger 3" exhaust. . Adding a 3.4" pulley to the Gen V supercharger on the series III engine is a different story. With the supporting mods, engine scans still showed KR over the engine RPM range. No matter how the tune was changed they were still there. I finally had to add a ZZ Performance intercooler and that eliminated the KR's. My engine also has other mods so my tune is now quite different from stock and that has some influence on the overall performance as well. Point is that you just can't add boost without supporting mods.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
You can try a different cam, a very responsive one. Open the duration 10 degress and tighten the LSA. The tight LSA will give you super quick throttle response and will give you that torque instantly, the extra 10 degrees of duration will carry that neck snapping fast torque to about 4300 to 4900rpms. There is no 3800SC that will catch you from light to light. That's what my Supernatural concept is all about, super quick acceleration. The amount of duration and LSA alloed will be determined by your compression.
what should I "title" the search.. "modding 3800sc" brings up NOTHING
Facetious?
I get wanting more bottom end... me too! I would think a 3800SC would be enough, I could get smoked by a 4 door Bonnevile SSEI with a blue hair behind the wheel! If the engine is already there then gear it is, no better way to get bottom end torque. or is there a better bang for the buck in a smaller pulley with whatever else it entails.What would it cost for gear change vs. engine (labor included)? What would your 60ft time difference be? If you want torque this is important.
It was a dark blue 2002ish Bonneville SSEI with Minnesota plates of the state bird the Loon that read "Uh Ooow Uh Oooow" or "I'm over here"
