Engine/Transmission (1994 - 1998) Compound / Twin Turbo Suggestions?

[MMcCallie]

Hey 12V, what are the max EGTs you can get your current twins up to? If I had the money, I'd probably want to try one of the smaller Garrett turbos instead of an S300G.

As far as mounting traditionally, with all of the extra heater and a/c stuff on the Excursion and the starter being in the way, I really don't see trying to squeeze everything in down there. If I didn't have the coil springs I could go out over the frame but I just think I'll have to mount the big turbo high.

So 12V, I take it you're not happy with the HT3B/26 in your combo?

 

[JHastings]

I have a set of twins that I just recently removed from my pickup b/c I needed the $$. They were a 35/12 over a 3b/23. I loved them and they lit pretty quick. EGT's right at about 1300 max under hard acceleration and boost at about 63psi. They lit at about 1600 rpm, but I ported my own 12cm housing and did a poor job I suspect and stocker would have spooled faster.

Prior to the 23cm I had a 26cm and I thought it was too laggy and I didn't have enough fuel to push it. I was much happier with the 23 and would have ahd a 22 if I could have found one (they are somewhat rare).

I do however think that my 35/12 was a huge limiting factor. I think it constricted it a lot and I saw extremely high drive pressures at high rpms. I think it was somewhere around 80psi backpressure vs. 60 psi boost over about 2500 rpms.

I now have a 14cm wg housing on my 35 and I think that would have been a better setup especially with a 60mm comp wheel (i. e. a 35/40) or even a Dodgezilla with a 62 mm wheel, but now we are not talking about a budget set of twins.

I have never been around the 62/12, but I would think that it would be a good top turbo if you already have it. I really think the 35 would be too small for you at that HP. Yes it will spool fast, but it wont support that much HP, unless you can do an external gate.

For a bottom turbo, the 3B is cheap, but old as hell and there are better turbos out there. I would have done a s400 if I had the money or even better (perhaps) a k31. K31's have a lot of good responses, but are more $$, but sometimes you can find them.

 

[MMcCallie]

Ok, I'm leaning toward keeping my small turbo because it does flow quite a bit. I just accepted a job in Alaska so I'll be dropping to sea level from 7,000' so that should help tremendously with spoolup, right? I'd like to know people's experience with the effects on spoolup traveling from high elevation to sea level.

My concern using an S400 is high end flow and heat. I think I have a very healthy amount of fuel and I want to make sure the S400 is enough turbo to keep my EGTs safe when pulling through mountains grossing 24,000 lbs. I wonder which will suit me better, the S400 or HT3B/22 or K31? Opinions?

 

[JHastings]

I think the s400 and k31 are going to flow more air than the 3b. Not sure of the differences in performace between the two, but I think they spin different directions and one might fit better than the other if you have space issues. Also, the k31 is wastegated.

 

[DCreed]

Which exact S400/3b/K31 are we talking about? they ALL come in different sizes and only the 3B is opposite rotation.

 

[12V Ford]

Hey 12V, what are the max EGTs you can get your current twins up to? If I had the money, I'd probably want to try one of the smaller Garrett turbos instead of an S300G.



As far as mounting traditionally, with all of the extra heater and a/c stuff on the Excursion and the starter being in the way, I really don't see trying to squeeze everything in down there. If I didn't have the coil springs I could go out over the frame but I just think I'll have to mount the big turbo high.



So 12V, I take it you're not happy with the HT3B/26 in your combo?

My max egts with the 0 plate are 1500 deg on a hard run and about 540 hp. With the 10 plate and about 480hp the max is 1400 deg. I use the valet when pulling heavy and the max egt is 1200deg. In valet mode the hp was around about 425 hp is IRC.



It's not that I'm not happy with the 3b, it's just that it doesn't fit the way I want it to in the truck. The thing I like about the s400s or k31 is that you can get many different wheels and exhaust housings. In the 3b your limited and finding them can be a pain. Plus I can get an s400 that will spool faster and flow more than what I got.

 

[DCreed]

I have a 22 3b housing if ya need 1.

 

[MMcCallie]

DCreed, I'm definitely interested. I have yet to be convinced of which turbo will be best for me, my HT3B with a 22 exhaust housing, a wastegated K31, or an S400 variety. It seems like the HT3B will promote easier piping if mounted above than the others because of its direction, but is so big I may have to clearance the hood, which doesn't really bother me. If the 22 housing will make me spool as quickly as an S400 or K31, yet still flow as much or better on the upper end, that would be what I'm looking for. Can anyone estimate at what RPM and psi the 22 housing would light and what max EGTs would drop to? If even a 22 housing won't catch up to the other turbos, I'll wait and do it right.

 

[DCreed]

Even with the 22 the 3B is inferior to the others in flow and cooling and spool. Also the 22 is faster to spool but may hamper the top end with drive pressure issues. Remember when planning a K31 exhaust housing is 1 1/2" longer than an S400 because of the internal gate.

 

[JHastings]

I think my 3b is pushing somewhere around 25psi tops. THat is with peak boost at 64psi and 39psi of it coming from my 35.

I know, I know... . you are supposed to gate it sooner, but I am getting my lowest egt's at this level and I have done lots of testing with changing my 35 gate... Kind of defeats some of the purpose of the twins, but with my gate closed, It performs the best.

I still believe the 3B is an old school turbo and if you got the $$ do something better. I only did it because I am a starving college student that was looking to find a cheaper and better performing route to a high priced single.