C5 engine decisions
TECH Fanatic
Joined: Jan 2018
Posts: 1,060
Likes: 198
While a 102mm throttle body would be ideal with a Fast 102 manifold, 102mm DBW throttle bodies are kinda hit-and-miss. I've got a NW 102 that won't open past about 20% that I still need to sort out, and I'm using an LS2 TB with my Fast 102 in the meantime. That plus stock heads milled to 60 or 61cc (I forgot...) plus 2" headers and a 3" x-pipe and Torquer V2 got me 475whp on a dynojet, so I support your plan. 
The Fast 102 plenum is a bit larger than the Fast 92 plenum, so there's still some advantage even without a 102mm throttle body. But I suspect I could get a few more horses if I can get a 102 TB that works right. (My "plan B" is to arrange two stock TBs in parallel.)
Tuned to idle at 850 RPM, it actually sounds pretty close to stock. A little rough, but it's subtle. Bringing the idle down to 700 RPM might bring out some chop, but I haven't tried.
The V2 is probably kinda small for a 383 though. If you go that route, you could go a little bit bigger on the cam to get more power without any drawbacks.
The Fast 102 plenum is a bit larger than the Fast 92 plenum, so there's still some advantage even without a 102mm throttle body. But I suspect I could get a few more horses if I can get a 102 TB that works right. (My "plan B" is to arrange two stock TBs in parallel.)
Tuned to idle at 850 RPM, it actually sounds pretty close to stock. A little rough, but it's subtle. Bringing the idle down to 700 RPM might bring out some chop, but I haven't tried.
The V2 is probably kinda small for a 383 though. If you go that route, you could go a little bit bigger on the cam to get more power without any drawbacks.
Last edited by NSFW; Oct 18, 2019 at 11:35 PM.
Thread Starter
Staging Lane
Joined: May 2019
Posts: 89
Likes: 3
From: Morristown TN
Well so far the fine folks at Texas Speed have told me the V2 is a great choice for a 383. I did go ahead and purchase a FAST but I got the 92mm instead. What is the call on using an LS2 fuel rail with LS1 injectors? Also I am trying to figure out transmissions and differential gearing. I am thinking a Z06 MN12 trans with either the OE 3:42 or move to a 3:73. Maybe even a 3:90. Yalls input would be appreciated
TECH Enthusiast
Joined: Feb 2018
Posts: 640
Likes: 297
From: Michigan
I have the Torquer V2 in my SBE LS1, I will say it's a great cam for canyon carving. As far as the MN6 vs MN12, it's my opinion that the MN6 is superior. The shorter gearing in 3rd gear paired with the same ratio 4th gear causes a huge drop in RPM between shifts. If you want more aggressive gearing I would keep the MN6 and get a more aggressive rear end. The only down side is that it will raise RPM in 6th gear on the highway.
If I did the rear gears I would go 3.90
And I think the cam will do nicely personally
The LS1 injector is taller than the LS2 injector. The LS2 injector is also fatter at the bottom. So they aren't interchangeable. There are adapters to make them work out if you have to adapt one style to another though.
And I think the cam will do nicely personally
The LS1 injector is taller than the LS2 injector. The LS2 injector is also fatter at the bottom. So they aren't interchangeable. There are adapters to make them work out if you have to adapt one style to another though.
That's another wonderful thing about the 92mm vs the 102. You can slap your LS1 rail and injector on the 92 but the 102 has injector bosses for the larger diameter injector bottom so you have to figure that part out and also requires new rails since the OE ones wont cross over the top of it and go down far enough. The FAST 102 comes with fat orings to stick on skinny injectors to convert the skinny injector to be used in the larger diameter hole that is in the 102mm intake but man I've had a ton of issues with the 102 and injector leaks that took a while to straighten out. The 92 is so much more plug and play, you just slap it on and go. The 102 ughh.
I did a 102 on a friends car and he had 60 lb injectors for it. For some reason they injectors were the right diameter but like .010" too short and they kept popping out of the rail. My buddy said he had to call FAST multiple times before he finally got someone on the line that was aware of the issue and they actually make a spacer kit for the issue. It was a nightmare and we had no idea why he kept having trouble because the paper work that is supposed to be in the box that mentions the issue was missing so we never knew and the first several times we called FAST nobody seemed to know anything about it. Rant over...
Last edited by 00pooterSS; Oct 18, 2019 at 05:18 PM.
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All that being said, I can't take too much credit, there's guys that know a lot more than me on here that I learn from daily on this site.
It doesn't hurt that I've been a tech over 20 years and at master level since 04 and have been obsessed with the LS platform since they came out lol so I try to absorb and learn as much as humanly possible myself.
All that being said, I can't take too much credit, there's guys that know a lot more than me on here that I learn from daily on this site.
On The Tree
Joined: Oct 2004
Posts: 98
Likes: 11
From: in a large steel structure
Well so far the fine folks at Texas Speed have told me the V2 is a great choice for a 383. I did go ahead and purchase a FAST but I got the 92mm instead. What is the call on using an LS2 fuel rail with LS1 injectors? Also I am trying to figure out transmissions and differential gearing. I am thinking a Z06 MN12 trans with either the OE 3:42 or move to a 3:73. Maybe even a 3:90. Yalls input would be appreciated
Thread Starter
Staging Lane
Joined: May 2019
Posts: 89
Likes: 3
From: Morristown TN
So after thinking it over, the heads I have and the cam along with the new FAST 92 I picked up, I went ahead and made the plunge. Texas Speed 383 aluminum short block. K1 crank, TSP H-Beams w/ ARP 2000 bolts, and Weisco pistons w/ 8cc dish and valve reliefs.