TPI- better mileage and power?

[try2pas]

I have a ZZ4 and after checking my budget have decided to stay with my engine for a while. Would TPI improve my mileage and if so how much in mpg ( I am getting 15 now on the hiway) And would it hurt my bottom end torque or help my bottom end? What about top end? Ideally I'd like more torque and way better gas mileage. I also am planning on putting in 700R4 for sure.

 

[mrvette]

15 years ago, having owned a '87 vette and loving the TPI performance but not loving the reliability, I sold the car and bought my Muncie 350 L48 '72 with 336 gears.....and so, as a stock car, it got 12-14 mpg and the Qjet was in decent tune....for a carb....
So put on a TPI system and with NO other changes jumped to 24 mpg cruising at 70-80 on the freeways....trips....

down here in Florida for the last 11 years.....I went to a hotrod 350 much like your ZZ4 but a step wilder in cam....and with a 200 4r tranny, same 336 rear, I did 22.2222 mpg at 90 mph cruise just last month....

so....I gained some ~100 hp easy, and with the o/drive got within 10% of the fuel economy....
looking back, maybe that L48 with the L98 induction wasn't such a bad deal afterall....but then again....there is the GRIN factor....

I think DPFI IF done cheeeply is a mucho better deal for any engine on a street driven car....but to spend 2+ grand on some install is a LOT of miles to get a payback.....but you see, I have had this car for 15 years now....

 

[Rodney Gold]

700r4 is your best bet , 3:1 1st gear for more vooma off the line and the 0.7:1 overdrive for waffling along on the highway.
You get the best of both worlds , performance and MPG.

 

[mrvette]

IF you have a '82 I can see sticking with a later model, say maybe a 88 up 700 tranny, otherwise to fit it into a earlier shark is a super PIA and expensive to boot....shorter drive shaft 100 bux, special/altered cross member...X bux, then we go for the rest of it...possible widen the floorboard on the pass side to clear the tranny case/pan....

simpler to to the 200 4r and get over it, almost a bolt in with no serious mechanical mods, you do have to do the lockup control stuff, and of course the gear select, and the throttle cable, and the dippy stick tube....

nothing a day can't sort out though....

 

[THORIN]

Put in a 700r4 in my 76 went from 11 to 23 mpg. I still intend to put in sequential EFI in at some point. My personal challenge or desire is not max horse power: but max MPG.

 

[KANE]

I have a ZZ4 and after checking my budget have decided to stay with my engine for a while. Would TPI improve my mileage and if so how much in mpg ( I am getting 15 now on the hiway) And would it hurt my bottom end torque or help my bottom end? What about top end? Ideally I'd like more torque and way better gas mileage. I also am planning on putting in 700R4 for sure.

I average around 18mpg in the city. Really, it depends on how much I put my foot down.

I can get 18 or much less... especially with lots of 3 to 1 downshifts

Stock TPI runs out of steam between 4500 and 5000 rpm. Long runners create great low end, but the trade off is on the high end. TPI creates gobs of low end torque. The LT1 intake (and miniram) are high end intakes. You can add better runners, port the plenum, add a bigger base- but it will still run out of steam around 5500 rpm.

I've really never need to go on the other side of 5500 in a street driven Vette.

I've done two swaps on C3s. It is really easy. The first one I did was back in '97, while in college and studying for exams (I needed to drive the car to school to get to the exams, so... I kinda needed to get it running QUICKLY!). I will never go back to carbs. EFI is a breeze once you learn how it works. The swap is straight forward once you get all the parts.