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Had car at dyno today. Everything checked out. Air/fuel was good and it was making 15psi@5800. Really felt like it had no *** down low at all. So the only thing we could narrow it down to was that the cats were clogged. What are the signs of clogged cats? Any other ideas?
on a normally aspirated engine, the easiest way to check the cats is to hook up a vacuum gauge to the engine.driving, under full throttle the vacuum gauge should read 0 psi, meaning there is little or no backpressure in the exhaust.a 3-5 psi reading would indicate a restriction somewhere.on a supercharged application its a little bit more difficult because you are compressing the air helping it get by the restriction.if your cats are clogged you will notice a relatively slow rpm rise.if your still not sure the best way is to remove the cats and install a temporary "test pipe" or h pipe.how fast are you spinning the ys at 5800 rpm? the ys, being a bigger unit than a typical s-trim will make more power at a higher rpm than it would at a lower rpm if its kept in the "fat" part of its efficiency map.according to vortech its max impeller speed is 60,000 rpm.if you are too low on the map you may not be spinning the ys fast enough.you can try a smaller head unit pulley to bring the boost in sooner but be carefull of peak boost pressure at your maximum rpm.
need some help please.
I did alot of research on this before I went with the YS. I talked to several people, including Spence and rel3rd, and they said it should be a good running combo. I can't see how stuffing 15psi compared to barely 8psi(powerdyne) would make less horsepower. I realize that I am not running the YS to it's full potential but it shouldn't make less hp in my opinion. The guys at the dyno figured I should easily be near 500rwhp with my setup. They feel that there is definitely a cork in the system somewhere. It's hard to describe, but is running really lazy down low. By 4400rpm the YS is making 9psi. My powerdyne was struggling to make 8psi at 5800 and it was pullied for 11?Quote:
Originally posted by WOHORSY
how fast are you spinning the ys at 5800 rpm? the ys, being a bigger unit than a typical s-trim will make more power at a higher rpm than it would at a lower rpm if its kept in the "fat" part of its efficiency map.according to vortech its max impeller speed is 60,000 rpm.if you are too low on the map you may not be spinning the ys fast enough.you can try a smaller head unit pulley to bring the boost in sooner but be carefull of peak boost pressure at your maximum rpm.
Which camshaft are you running in this car? What is your combination? What fuel injectors?
500 hp seems to be a realistic number.if your air/fuel is right i can't see you making less power with the ys.did you make any other changes when you switched to the ys?sometimes the smallest thing can have a big effect.if no changes were made i would do a compression check and a leakdown check if needed.a fuel pressure test wouldn't hurt and make sure your clutch is not slipping due to the increased hp.a cat usually won't go bad overnight unless the engine was running rich long enough to overheat them.
Brcuda - Anderson B-2
WOHORSY - I put the YS, holley intake, 42lb injectors, 80mm Pro m, AFM powerpipe, 70mm TB, and fuel system on at the same time.
if your BTM is correct(did you physically check to see that its pulling 15° under boost). you dont have enough timing. at 15psi you have a total of 11° if your using the stock EEC, this would also explain why you have no bottom end. Move your base timing up to 14° and move your BTM back to a half, this should give you 22° total at 15psi , that should really wake it up, I would also fatten it up a little bit just to be on the safe side until you get the timing closer.
Your dyno guys did not question the total timing only being 11°? or did they not have anything to do with the tuning?
They did say we could try to add more timing. You're saying that would cause the car to be so lazy on the bottom? I realize more timing will help with the bottom, but I just wanted to keep it safe until I could get it on a dyno. I'll try setting the timing to 14*. What should I set my fuel pressure too? Thanks.Quote:
Originally posted by Spence
if your BTM is correct(did you physically check to see that its pulling 15° under boost). you dont have enough timing. at 15psi you have a total of 11° if your using the stock EEC, this would also explain why you have no bottom end. Move your base timing up to 14° and move your BTM back to a half, this should give you 22° total at 15psi , that should really wake it up, I would also fatten it up a little bit just to be on the safe side until you get the timing closer.
Your dyno guys did not question the total timing only being 11°? or did they not have anything to do with the tuning?
more timing gives you a butt load more torque, your total timing should be in the low low 20s, yours is 11°, that is a HUGE amount of power loss. set your base to 14 and BTM to 1/2. take it for a ride and let me know what your impressions are. I like to run my FP at 40 with the vac hooked up at idle. A little tid bit, changing my timing 6° from 3000 rpms to 6000 picked my car up 4 tenths in the quarter( had FAST calibrated wrong to the distributor reference)
My fuel pressure is set at 40 with vac. connected. I'll give the timing a try tomorrow and let you know what happens. Hopefully, it will be a big improvement. As usual, thanks again Spence.
Quote:
Originally posted by blwn88cpe
Brcuda - Anderson B-2
WOHORSY - I put the YS, holley intake, 42lb injectors, 80mm Pro m, AFM powerpipe, 70mm TB, and fuel system on at the same time.
your combination sounds ok.i am assuming when you installed the lower manifold you disturbed the distributors position.heres a tip.before you remove the distributor next time make a mark on the center of the rotor and a matching mark on the lower distributor cap.this helps you get the timing in the ball park when you first fire the engine.of course you will need a timing light to check your base timing.i run 12 deg base timing with 1/2 turn on the btm.i have tried up to 15 deg but it was too much for the 94 octane i use around the street.you'll have to see what works best for your combination.also dont forget to tighten the distributor holdown and to reinstall the spout connector.
Spence, I set the timing today and it did seem to wake the car up a little more. I heard a little pinging so I turned the BTM to about 3/4. Any more ideas? Should I drop the timing back to 13*? Thanks.
I did have a question though. Shouldn't I be able to blow the tires off in second gear(maybe even third)? I know it sounds childish but I figured that when I was leaning on it, it would spin the tires. I did have an almost full gas tank by the way.
what kinda gas are you running?
93 pump