TB spacer

[GrimGreg]

Anyone know of one available for our throttle bodies?

[RedPath88]

88 has one on his TBI engine...

 

88, you refer to it as "custom" did you make it? How much of an effect did it have on your engines performance?

[88pathoffroad]

So far I notice no difference in power or gas mileage. I made it out of a $1.99 3/8" thick polyethylene cutting board, using the stock mixture heater as a pattern and using a Dremel with a Roto-Zip bit to cut the PE. I cut two pieces, for 3/4" of spacer and gasketed between each piece. I had to buy new studs and damn, they're kinda expensive, like $3 each or so.

 

Here's a pic.

[hardwaretoad]

So, other than an additional 2 possible leak-points, what's the advantage?

 

Curious peeps want to know...

 

BTW, congrats on getting your forum back up... :type:

Edited July 31, 2005 by hardwaretoad

[88pathoffroad]

The theoretical advantage is to space the TBI higher off the intake to gain better fuel/air mixture for all cylinders. As it sits stock, the F/A mix leans out the cylinders on the passenger's side until you hit about 75% open throttle due to the orientation of the throttle plate. *shrug*

[Precise1]

Hmm, makes sense... Sounds like a good reason not to buy one of them there 2 door thingamagiggies... :o

 

B

[transworldmoto]

where did you get the materials? i would like to do this to my tbi, since i just bought a whole new tbi unit off a 1989 with 40k on it. can you tell me what you used for the studs too?

[88pathoffroad]

A $3 white polyethlene cutting board, and longer studs.

[transworldmoto]

sweet! off to the hardware store!

[transworldmoto]

and that 3/4" of lift on your tbi didnt effect the bolting of the "air box" to the valve cover? or did you have to get longer bolts for that one too? :confused:

[88pathoffroad]

Shoot, I trimmed off that tab long ago. Now all I have to do is take off the wingnuts and the air cleaner comes right off.

[mws]

Hey Aaron - Love seeing the real world feedback.

A couple of the TBI spacer marketers are now offering versions with the separator between the bores partially eliminated in an aerodynamic looking way. The claim is that this improves balancing between cylinders at low rpm and improves peak power at higher rpm as each cylinder can draw from both bores of the TB. That theory and $5 will get you a cup of coffee at Starbucks...

But, then again, that theory also sounds an awful lot like the old Yamaha V-Boost system on the V-Max. On that engine, it worked and made a huge difference as the bores were undersize for the displacement - so letting cylinders breathe thru two bores eliminated a major restriction.

 

I wonder if the bore diameter in the TBI present a power limiter to these engines at high RPM?

 

Are the bores separate or joined in your plates? Have you tried the other option? Wanna be our guinnea pig?

[88pathoffroad]

Hey, that's not a half-bad idea. I could make one like that and put it in there. Dunno when I'll have the time, though.

 

My spacers just have a single bore, all the same size. I bolted the raw PE plates to the mixture heater and then cut them to fit that way so they're all the exact same.