My twin supercharged tbi 350 miata build

[Shawn1989]

his reply word for word:

wow
were talking apples to oranges here, but I will let you know what I've done and you can take it for what it is. I sold my cavalier about 2.5 years ago as I was unempoyeed and did not want to file bankruptcy, so luckely that pulled me through until I got a job, sad day that was..

In anyrate,

My ECM was not tuned, however I did have a custom tune from superchips. Since my TBI was an high impatence injector to start, I was already in good shape. I had a 10:1 FMU for fuel manaement. Only thing I had done was port and polished the heads, all stock bottom end. Through the research that I've done, I know that the block was good for about 350HP (no kidding). My goal was no more than 300 (which I've never reached) reached about 213 or so at the wheels. (still isn't bad consitering that the stock was 90HP from the factory. Poor 2.2.

In your case, not sure where to begin on that one since your dealing with a supercharger over turbo. In my opinion, turbo's are easier to deal with but each case is different. No wide band. I had mine tuned in from a local speed shop here in dayton, did an ok job. drove it about 3000 miles with no issues, check engine line or anything so I'd say it did ok for me. But mine was more for show. I've taken it to many of shows and won. But didn't want to be one of those guys who did all show and no go.

I hope this helps.

[Shawn1989]

http://home.windstream.net/mcfly/tuning_fuel.htm

i just read this whole thing.
he didn't tune his via the pcm, how reliable do you think this is and how good will the engine run?

[Shawn1989]

Progress.



I began painting the inside, but then the wires wanted to put up a fight going where they needed to go. So i ran the wires and now i'll go back in, sand down, tape, and spray around them to clean it all up



Running engine stuff through the trans tunnel rather than the firewall. It should help clean it up a little bit.


Painted the bay, came out good for being the good 'ol Rustoleum rattlecan.


Ran the fuel, brake, and clutch lines today since it was all dried up.



I should be able to get the inside of the tub completely redone tomorrow. I'll post pics; then it will be time to work on the engine again.

[Shawn1989]

Well i didn't get to the inside of the car, instead i worked on the blowers a little bit.

I fabricated up a mount for the tensioner. I got rid of the sway bar due to it being spring steel and you can't weld it [I wasn't aware of this; so thank you to someone who pointed it out] and i replaced it with steel stock. I took the tensioner apart, drilled a hole in the housing to reclock the spring for the area of tension i will need. I also filed down the "stop" a little further back so it has more room to retract and keep tension on the belt rather than maxing out and letting the belt get sloppy. I put it back together and these are the results:





I was also looking to see if the blowers mount is flexing and it is. I am not sure if its flexing just because it's only tac welded together, but either way, I'm going to add a few couple of supports on each side just to be safe.

That's it for now, I'll start working on the passenger blower tomorrow. I need to get another tensioner from the junkyard and another belt from autozone.

[Shawn1989]

drum roll please!



few adjustments are needed, BUT there she is!
gotta take back apart to fully weld, add bracing, and paint, but overall i am satisfied.
alternator and vbelt slipping is my main concern though :/

[brian617]

Your superchargers will be turning different rpms.

[Shawn1989]

Your superchargers will be turning different rpms.

I thought this too...... SO i marked the pulleys and supercharger housing, turned the crank by hand, they lined up perfectly.
I'll upload a video to show you.

[Six_Shooter]

The drive and driven ratios ARE different between the two superchargers. They might be close enough that a single rotation looks to be close, but run it for several dozen rotations and they will get out of "sync".

Honestly I don't know why you are trying to run then from different belts. You will be much better off to run them off a single belt. The only exception would be when using a jack shaft where a single belt drives an intermediate pulley and then both superchargers are run from that intermediate pulley.

[brian617]

I thought this too...... SO i marked the pulleys and supercharger housing, turned the crank by hand, they lined up perfectly.
I'll upload a video to show you.

Its simple drive-driven ratios. One belt runs strait off the crankshaft, the other is being turned by the water pump which is driven by the crankshaft. The water pump pulley would have to be the same diameter as the crankshaft in order for the ratios to be the same. The water pump pulley is turning faster than the crankshaft.

[Shawn1989]

Correction. Spun it 10 times, passenger went a little further

[brian617]

I also agree with the single belt, seems like you have a lot chances for belt slip.

[Shawn1989]

I also agree with the single belt, seems like you have a lot chances for belt slip.

People said a single belt as more chances of failure..... that was the original plan


here is how much faster the passenger is after 10 rotations...... would a 10% overdrive pulley on the drivers side possible fix this? i know a single belt would but going through that hassle of rebuilding everything sucks :[

[Skinny Pedal]

Whats the size difference in your crank pulley and water pump pulley? There is your % of change you need.

[Shawn1989]

Ok, about the single belt......

Can i run it like this without any problems? [comes in contact with the waterpump twice]

IF so, i can pick up another belt right now; all i would need to do is add another idler where the red dot is.

[brian617]

Lots of head scratching there to maintain proper rotation and apply enough contact patch. Any idea how the gentleman who had already done this ran his belt setup?