Turbo Strategy


Active Member

Well I need some advise. First off I'm building a heavy hybrid (4000lbs approximately) and for starters I'm limited to a stock BRF tranny till I can afford a full tilt one so power is restricted by the rest of the drivetrain durability. This brings me to the real question, should I go for the full blown turbo, a CPT61BB, and run it at much much reduced booste to keep the power down, or should I get something smaller like a used TE44 and run it a bit wider open? Both will be external downpiped and I'm pretty sure all of them use the same style of downpipe flange so I can interchage my "uh-oh" stock exhaust housing that I'm using for mockup for the real thing down the road.
Commentary welcome and for more information, I plann on keeping the stock D5 or maybe upgrading to my planned 3200 stall converter depending on the turbo. Also the car currently has a 3.23 rear so that doesn't help the get up and go much either.

Last time I weighed my 86 T-Type with me in it and my usual trunk-o-junk that I'm too lazy to take out at the track, it was 4060 lbs going down the track so your 4000 lbs isn't that unusually heavy. Do you care about pump gas performance or full-tilt race gas performance? It sounds backwards but for pump gas you want a bigger turbo that will be more efficient while with race gas go a little smaller to get better spoolup and 60' times and use the octane to let you run more boost to make more power. I run 93 octane pump gas, no alky at all, and have a V2 frontmount. I've run a TE34 (one tick smaller than a TA49), a PT54, and now a GT67 p trim, and I love the 67. I have a 10" roughly 2900 rpm stall Yank converter (don't ask :)) and it is not quite enough for the 67 but was plenty for the 54. Besides, with a heavy car you have to worry more about wheelspin so think of a little lag as traction control. Besides, I run a 3.8 and I think you are building a 4.1 so you will have no problem spooling a 67 with a 3000-3200 stall converter.
It's a '64 Riviera which shipping weight lists at 4200lbs, loose 400lbs in the copper/brass radiator and AC condensor and motor swap and I'm guessing on average it will weigh around 4000lbs without driver. So I guess its not horribly heavier than some TR's but its no light weight and we all know heavier cars are harder on parts due to the weight and the effort needed to move them with the kind of athority we like.
Anyway, yes I'm building a 4.1 so I have 25cid on the stock 3.8L. Its a street car so pump gas only with a 2 stage controller that goes to high boost with the arming of the Alky system eventually. The most important thing about this question is what to do now for the temporary combo. I have every intention of adding a custom intercooler, a CPT61BB, a full tilt lockup tranny and some other things like possibly 3.73 rear gears to help get it out of the hole faster but for now I need to build for the limits of a stock tranny in a heavy car. I can't blow the tranny, I won't be racing it but Hot Rod Power Tour is lame if you pedal it everywhere so there will be some agressive acceleration. How efficient would a CPT61BB be on the street if I kept the boost low?

Once you make your converter choice you can pick the turbo.

3200 stall get a CPT66BB. :)

3000 stall will work easily with a BB61.

Stock D5 at pump gas boost levels it won't matter much power wise between a 44, 51, 60, or a 61, excepting how long it takes to spool one.

BB will help there.

You can buy big in advance but if the tranny isn't in the car I'd get the converter done and new turbo now.

But then again building the tranny first is more important on a driver anyway, as you can easily slip the 2-3 on a stocker with a stock D5 and a used 44 with a stout motor and a good pump gas tune. :frown:

So you either need to define the goals again, or find a whole heap of $$$ to do it right (subjective of course) the first time. :cool:

What parts do you currently own that are in good/great shape?

My WE4 is 3955lbs. race weight, with me a whole 160lbs.

My GN is 3850lbs. race weight, with the same driver. :p

I'd also build the $150 DIY alky. regardless of turbo and converter, after the tranny is beefed up, nobody really wants to run pump gas boost levels.

I think your decisions need to be based more on your personal info. and parts on hand and when the new stuff can be purchased etc. rather than by others via internet guesses, although I did try. ;)
64 Riv Project

Think your project is going to be awesome. Think your right on in going to a more modern technological Turbo like the CPT 61, that's one I'd love to upgrade to. I would think about maybe for now during "MOCKUP" even going with a stock turbo and stockD5 and using what money you save to upgrade your injectors or cryo block:eek: , get the Motron 60's and TT chip to support the CPT 61 Turbo that you're eneavitably going to upgrade to. Infact have a stock turbo for 100 dollars if your interested. Salvage6 has a good point about tranny build 1st and deciding what TC to use with the CPT61.

I don't know how far along you are on your 4.1 block build, but in what I've read about them having a tendency to get fine line stress cracks along bore. Was wondering if Cryoing the block would help in alieviating that inherent problem by relieving structural stress from the block and making it stronger before machining/boring . Would definately Make it stronger for use in your 2 ton Rivy project. Read alot on cryoing and alot of racing teams( from circle track to drag racing) have it done religously, to get more out of their engines .trannys, brakes,3rd members. One of the cryogenic outfits actually had a price list and an interesting history and overview of the process.

The only reason I mention cryo is if that lil 4.1 is going to move that behemoth with authority she might be strengthened a little on the bottom end. I think too much. Even if you don't cryo your 4.1 block(4-5 hundred)yes it's probably overkill the money you save could be used towards a external wastegate Downpipe for the CPT61, or 3.73's. Anyway glad to hear you went with the 64 RIV a great and beautiful car.
The Long block is done. The short list: Billet caps 1-3 (girdle won't clear the chassis), full forged rotating assembly with 8.3:1 pistons, champion CNC iron heads, roller cam, 1.65 T&D roller rockers, TA custom 1 piece pushrods. External wastegate downpipe is going to be custom but I'm negociating for a fair deal on an elbow. Headers are mild steel ATR's. Motron 60's are a given.
To further throw a loop in this, the ECM is an L67 3800 supercharged ECM so I can laptop program it vs feed it chips, so I'll be programing it to start.
I've been thinking about building the tranny first but I'm not sure I can afford a $2500 tranny and the other stuff.
I still would go with the 67 now - why buy twice. The GT61 is really good with high, high boost levels that you can only do on race gas or alky, but on pump gas from what I've read it is about like my old 54. The 67 spooled just a hair slower than the 54 but on 93 octane is about .1-.2 sec quicker in my car. Just keep the boost down to whatever you think the trans will stand. Why buy a smaller turbo that you "turn up" to some hp level set by the trans, instead of a bigger turbo that you turn up less to reach the same hp - just to say you are running x psi boost? Do the motor and turbo now, and stay with the stock converter until you build the trans. That way if you blow the trans you won't have to pay to have the converter cut apart, cleaned, and checked. Lag will be in the 2 second range between stomp and 5 psi boost from a dead idle, but not nearly so noticeable hitting it on the highway. My $0.02, anyway - cheap at half the price :).
I love my GTQ 67 on my street car. Right now it has a 2800 stall. It is a little tough to get it spooling but once it does:eek:
I can share my experience with that turbo at least...

I had a CPT61bb paired with a Tial 38mm gate. I had a stock longblock with MSD50's, PTE FMIC, 93 octane chip. I had no boost controller hooked up yet, so I was stuck at 13psi which was the spring in the gate. With a 0psi launch (1.85 60 foot) and 13psi going down the track, it went 13.40 3 times. The converter was a 9/11 lu advertised to stall at 3000. The car was 3585 with a full tank of gas, spare tire, withOUT me in it. :D

A bit later I got the boost control feature working on the Translator PRO setup and it spooled QUICK! I'm sure with a small cam and a little work on the heads, this turbo will rock with some boost and timing in it.

With that being said, even though you are heavier, with the extra CI and converter, I'd go with a 66 or 67 ball bearing and be done with it.
I don't recall all of PTE's nomenclature but if you check the turbonetics vs garrett bb sticky thread Patrick spelled it all out. I recommend either the 67 or 66 over the 61, and the 67 if you will run good heads and mostly pump gas because it is better in the under 25-psi range and the 66 on race gas is reported to be better for 25-30 psi (but some have run 28-30 psi on the 67 and made great power). For either one I'd stay with the P trim turbine and 0.63 a/r housing for better spoolup, and dbb if you can afford it. The 67 can be had with the small shaft p trim turbine so that is the cheapest combination but it might not last as long between rebuilds as a big shaft if you plan on many 10,000's of street miles. I'm running the small shaft and no bb but have less than 5000 miles on the turbo so far. You could live with a stock or modified stock converter but then when you do the trans go to a 3000 or 3200 stall 9 or 10" converter.
Well, I was thinking the Turbonetics one since they have the no questions warranty and though I'm a fan of the dbb and the GT wheels, having a turbo thats heavily waranteed apeals greatly to me. I'm not totally sold on either though I know I want ball bearings vs a journal bearing unit. Something else a friend pointed out is that its a lot easier to swap turbos than to swap trannys, especially since my crossmember is welded into the frame since its an X-frame not a perimeter.
66 single BB with 3200 stall with heads and cam. :)

I think your money availability and work flow will most likely determine your final build up.

I wouldn't bother with a 44 with heads and cam. unless it was already in your possession (free) and ready to go.