I current have a stock 5.7 tpi engine in my my car now.I just had a modified 700r4 built from the good fellas transmission in stalled in my car for my 4.8. would like to start the swap by the fall.how different is the drive-ability from a 350 tpi would it be compared with a 4.8 can you really feel the power difference between the two.

 

is there any body out that has done the swap comment on their experience

 

bump

 

My girlfriend drives an 85 TA with a 350 TPI. Shes pushing about 340hp out of it.

I have an 85 Z28 with a 6.0L LQ9 (LS1 intake/PCM) thats pushing about 450hp.

Both cars when tuned are very driveable in the city and on the highway.

Biggest difference I find is in low rpm / low speed situations. The engines are 2 completly different animals, but the LSx will always idle smoother, and will handle driving really slow (15mph ish) smoother than the TPI setup.

On the other hand, the TPI system runs out of juice at about 4500rpm. I rev the LSx to 6000 before I shift.

Stock, the LSx is much easier to tune (no chips), but if you get an EBL ecm, its much better.

Gas mileage is similair, but they're two completely different animals...

She's had alot of distributor troubles, the LSx's ignition system has been a gem so far...

It's all in how you build the 4.8 thats going to define the driveability.

 

Both will perform when built right
But LSX will be best bet when it comes to drivability and easy to work on
With sbc you can't there will always be some nick nack that will pop up is distributor , I'm proper tv cable setup oil leak to remove intake and heads are a pain but you never know when something is going to happen

Power on stock tpi falls of at around 4000 rpm after that your not really going much of anywhere but from take off to 4000 is fun as hell

For LSX you will lose that low end but you can get a cam to creat a table top tq curve but tpi will still win on down low tq BUT after 4000rpm she will keep pulling up to 6k depending on engine setup so you will feel that

Instead of a 4.8 I would suggest a 5.3 can throw in a larger stock cam and if you have $$$ for t56 and get a tune seen guys get 30mpg on highway I heard even some mild ls1 getting close to that also with t56

 

Who gets 30 on the highway? My friends in vettes have but thats on long trips going the speed limit. An fbody isnt going to get 30mpgs.

 

Of course going the speed limit and very light foot on near stock engine and tune with a t56 not a auto
Modifications heavy foot will change that
Yea it will but I'm not here to argue that
But I've seen range from 27-30 mpg on highway with t56