Looking to see if anyone has experience using this specific kit. Saw it pop up while browsing and have to admit it intrigues me, especially since the price seems to have come down.

https://speedmaster79.com/Chevy-GM-L...Complete-Satin

This would be going on a 2000 C5, LS3/L92 6.2L, SBE and stock heads (no porting) with a BTR LS3 Stage 2 cam (Specs: 225/238 .612"/.585" 113+3). T56 and 4.10s. Intended use is a weekend warrior with a bunch of casual road racing use in the warm months. I am not too concerned with overall power gains, more so interested in the increased driveability and mostly the sound! I’m thinking about adapting an LS1 or LS2 throttle body to act as a servo with custom linkage to actuate the 8x throttle bodies mechanically, so DBW vs DBC is not really a concern.


Concerns:

-Need to figure out motion ratio of DBW TB vs ITB linkage to make sure they’re 1:1

-Need to fab up a vacuum manifold to supply vacuum to MAP, brake booster, HVAC system, and maybe a port for IAT. I'd need to tap a fitting into each runner between the throttle blade and the head, then join them at a common log mounted to the valley...

-PCV – can add a port on this vacuum manifold to plumb similar to an OEM setup – or just run lines from the valve covers to a vented catch can.

-Filtration – I only drive my car on nice weather days, so elements aren’t a concern but there is still the issue of general dust/debris/leaves/etc. Filters/screens look goofy and rob power

-Tuning – obviously MAF is going bye bye and I will have to convert to Speed Density, anyone know of any other special considerations when using HPTuners to calibrate an ITB setup?

Any other first hand input/experiences are welcome.

 

Speedmaster is hit and miss.

 

Can you elaborate more on that? Have you used their products (specifically this one)?

 

Speedmaster has a spotty rep when it comes to QA/QC, and quality in general.

 

Surprisingly, this intake performs well and sounds amazing.
But yeah, Speedmaster can be hit or miss. Its likely that when you get the intake that there are casting flaws you'll need to clean up.

The throttle linkages should be shafted(ish) together, so you'll just need to run a throttle cable to one side, and then use an intermediate linkage to connect it to the other.
They may or may not include that linkage with the intakes still.

I'm pretty confused by "Need to figure out motion ratio of DBW TB vs ITB linkage to make sure they’re 1:1". I would just ditch all DBW completely and run a cable throttle.
For the vacuum related stuff, I would just the cylinder 7 runner and put a fitting in it to run a vacuum block.

 

I was looking to do a ITB set up on my 02 Z06... I was giving the speed master kit a "hard look" but due to the issues with Linkage shaft binding, I decided to pass on that setup. with the amount of $ involved with a good, well thought out ITB... I felt is was more cost effective to go with the dual plenum intake that Holley sells.. (Im waiting for it to drop down to $750 like it did last year at xmas time) like you I want to road race, so, while I could retrofit a LSA blower, I really don't want to deal with more heat and complexity... the performance is similar to ITB's but you can use a Torquerush X2 to piggy back a second LS3 throttlebody… not saying this is the route you should go with...… Im just showing a alternative that you may want to look at.

 

Not to mention the don't run well in speed density mode with out a shared plenum. Alpha N is about the only way to correctly tune them in.

 

I don’t mind cleaning up a casting or making sure a linkage moves freely, that’s almost expected on a kit this price. What I meant by the 1:1 comment was that I need to ensure that a 90 degree range of motion from the DBW TB translates into the exact same range of motion on the ITB blades. This is determined by the length of linkage, where it attaches on the shaft of the ITBs, etc.

Thanks for the input. I actually really like the novelty of 8 individual runners, so if I’m going to jump in, might as well go all in. I’ll keep your suggestion in mind since I may build my own dual plenum one day.

Is HPTuners capable of supporting an Alpha N table? If not, how does one tune this setup in HPT?

Is a small vacuum manifold with the OEM MAP sensor installed in it, with 1/4” lines running to each runner, sufficient to give an accurate MAP signal? I hear that above 30% throttle the MAP reads ambient (100kpa) anyways.

Installing 8 vacuum lines is not a ton of labor, especially since it can be done off the car on the comfort of a workbench. I’m willing to do that if it means I have a more accurate MAP signal.

 

I'm still confused as to why you are trying to correlate the ITB linkage travel to an electronic drive-by-wire (DBW) throttle body.

 

I suppose I should have explained earlier, my bad.

Here in NYS we have an annual emissions inspection (plug in for OBD2, but no sniffer). No "CEL" can be illuminated on the dash.

My assumption is that converting the C5 to drive by cable, in order to drive the ITBs, will require a couple things:
-PCM swap to one that has an IAC driver
-adapting a TPS and an IAC onto the ITBs
-installing a pedal from some other application that pulls on a cable, this also means I will lose my N2MB WOTBOX functionality since it takes its signal directly from the ETC

The PCM swap is what concerns me as the C5 was never offered DBC, and I don't know how installing a DBC will affect the rest of the system (BCMs, etc).

If I didn't have to pass emissions I wouldn't care for a minute and would just convert to DBC, but then you also lose Cruise control, ABS, and Active handling/traction control. This is primarily a street car so it'd be nice to retain those features

 

So you're going to use a DBW throttle body, and create a linkage system that attaches to it to drive the ITBs?

-You can disable whatever codes you want in the stock PCM so that they will not be detected, even with an emissions system scan.
-You can step up to a PCM that has both IAC and DBW control. They are out there. You may even have one.
-The ITBs already have a spot for a TPS sensor, but not IAC.
-The N2MB works perfectly with a cable throttle body, I ran one for several years.
-Cruise control can be added as long as you can find a way to mount the stock cable cruise module. Wiring it is simple, you can even use your stock cruise buttons to control it.
-ABS will still function without DBW.
-Active handling and traction control can still function without DBW. You will lose the throttle control portion, though.

 

Re-engineering all those systems that are already functioning seems like a hell of a lot more work than building some linkage.

 

If you're building the linkage, why does the throttle range of motion matter? You decide the ratios yourself.