Magman

iTrader: (6)

I'm thinking of converting my 1990 350 L-98 TPI to Vortec. Am I correct in understanding that this intake system (manifold & heads) are completely different? What else needs to be changed to run the vortec heads ie..intake/wiring/ ECM? My L-98 is basically stock now but I am interested in joining the 12 second club with some nasty street manners. Would I be better off to rebuild the current setup with new heads/ cam and stroke it to 383 or go for a 383 HT? Thanks in advance.

unknown_host

iTrader: (1)

Ditch TPI if you are going vortec.

wesilva

iTrader: (35)

You will have to change the base of your TPI to a Scoggin-Dickey base (the only Vortec base currently available for TPI). The cost is about $425 with gaskets. They also have a dedicated EGR set up to maintain a legal smog control. You shouldn't HAVE to change anything else but you have a nice start to build on in the future.

unknown_host

iTrader: (1)

Do you daily drive your car and do you have to pass smog?

poncho@home

see sig....I am happy with the results so far over and there is still alot more in her.

I figure I will be MPHing 103-105 mph when I am done...that's in the heaviest 3rd possible (3750 with driver)

wesilva

iTrader: (35)

But more importantly for big MPH's, you have the most aerodyanamic 3rd gen.

Magman

iTrader: (6)

Thanks for the input. I'm leaning towards building the 383 and adding the Holley Stealth Ram to help it breathe. My IROC is a hobby, (3rd vehicle) mostly street, some strip. My plans are to see mid to low 12's at the track and still maintain street manners. I havent made it to the strip yet since I purchased it in June 03, the butt dyno says 13.8 - 14.0.
No, I dont have to smog test it , yet!

With the Vortec it sounds as if I would have a lot of rewiring and maybe dump the ECM? Not sure if I want to do that if I can get similar results from the above option.

Thanks again. Any other insight regarding the Vortec is welcomed.

Received Hooker 2055's today, ship to Jet Hot tomorrow. I didnt order through Jet Hot because I wanted to cut and weld the air tubes. Cant wait to install

305RSlc

Well this might be of help. You looking at switching to vortec. I'd say dont' mess with that if you are keeping TPI. However, have you looked at the Fast Burn heads? They are the aluminum vortecs with 62cc and 2.00/1.55 valves and 210cc intake runners. They are ready right out of the box. And heres the good part: You get the flow of the vortecs but the Fast Burns are tapped and drilled for both types of intakes,(stock and vortec style) so you could keep your stock TPI. They are around $1300 from Pace or Summit or Jegs or...well you get the picture. I'd say ditch the TPI anyways and go HSR or mini ram. Those would be good to getting you into the 12's with very few problems.
Lc

poncho@home

The stock TPI intake base will not properly seal the elevated ports of the fast burns or iron vortecs. It's not only the bolt pattern that is different, it's also the port design and you would be hindering performance by not using a dedicated vortec intake. I researched this thouroughly.

Where'd you get this from? The vortec option is as direct a bolt on as can be. Remove old heads, install vortecs. Remove old TPI base install new SDPC TPI base, bolt everything back up as before(except EGR or use EGR kit from SDPC).

Stock wiring, stock everything else for that matter. 5 hour job tops.

While I agree that aerodynamics help, consider that I am roughly 200-400 lbs heavier than Irocs and Formulas, I need 20-40 HP more to make the same MPH as them, minus the benefit from the slightly lower CD.

Plus I feel my MPH aren't telling the whole truth. My bottom end and mid range are very strong, and once I add a cold air package, ported plenum and runners I am sure that will help my top end out. I plan on hitting 105 MPH in perfect conditions, but 103-104 on a regular basis. All this with a never touched bottom end, stock cam and full street trim, weight, tires and tank of gas.

wesilva

iTrader: (35)

My appologies. For some reason you said "MPH" and I immediately think "Silver State Classic", "Salt Flats" etc. where your weight is no issue. In fact, for high speed runs, the weight helps stability. The best 3rd gens for the Silver State are the 'birds. For drag racing, I can see the weight being a hinderance. Should have gathered that by the 105 MPH goal. On a top end run that dude should be good for 160.

poncho@home

No apologies necessary.....just clarifying things...

I remember seeing a show on high speed passes and in fact the 3rd gen birds, in particular the 85-90 where the most aerodynamic hitting very low CDs in the .2x range....

My car should be able to hit 160 with the power I got now...just need to find a road and try it!!! J/K ...I would never try it that on public roads!!!!

Roads88

Poncho@home

not on topic but... with a 700r4 what did you do about the WOT passing gear issue? I went with an upshift sleeve and it jumps back and forth from OD to passing gear.

Makes me long for a T-56.

poncho@home

not sure exactly what was done....my transmission was upgraded by a local tranny specialist, it works well.

One of these days I need to get him to enumate what he has done

Roads88

if you find out? Please shoot me an E-mail

poncho@home

will do

Magman

iTrader: (6)

Poncho@home, thanks for clearing things up! Its a lot easier to see my available options now. Sounds as if the Fastburn heads, a decent cam(??) with the SDPC intake base topping off a stout 383 block, should head me in the right direction. I'll be sure to do the research and talk with tech reps before making any purchases.

1bad91Z

iTrader: (1)

I have a combo similar to what you are trying to do, only mine is a 355 ci and my heads flow ALOT more than a set of out-of-box- fastburns. You dont need a stroker to make a bunch of power. Save that money, build a 355ci. and put that extra money into porting those fastburns !! You wont be disapointed !

A six-speed doesnt hurt either. It's a blast to drive! :hail: