Hey guys, so i'm pretty happy with the car cosmetically now, it just needs some more fine tuning. Took it the the 1/4 mile track, and was a bit dissapointed. It was a very hot and humid even foggy night. The best i ran was a 15.7. My concern is that i feel like the car doesn't pull very hard all the way to red line, it pulls great till about 6500 RPM. I have a fresh streetport rebuild, Weber 48IDA carb, LSD, ghetto headers, carbon kevlar clutch. I tuned the carb with a wideband and is running 14:1 AFR Full throttle. I suspect my exhaust is too restrictive and accounts for the high end power fade. It was straight pipe to a magnaflow before but i was getting noise tickets, so i had a muffler shop install a baffel type resonator, and he said it'll quiet it down but it will be slightly restrictive. I'm thinking this is the source of my problem. Or is this a worthy time for my mods?
Thanks alot, Matt

 

Visually that thing is beautiful. I absolutely love black FB's.

As far as the exhaust goes, I don't know if one resonator is going to be enough of a restriction. I mean obviously it is going to restrict some, but I don't think it is going to restrict it enough to make enough of a difference to change it.

 

What's your 60' time?
What kind of tires?
What's the diameter of the exhaust pipe?

 

Looks like you have some well thought out modifications, but I have to ask. Upgraded fuel pump? Either that or ignition. This is assuming of course the exhaust isn't the problem. Lots of stock ignition systems either can't keep up with the fast pace of high RPM's or the amount of power delivered drops off.

 

My 60 ft times were 2.255, I was using Bridgestone Radial T/A Performace All seasons, 195 width on stock rims, My MPH was 85.43. Exhaust diameter is 2 1/4 inch. I actually have 2 Free flowing resonators, a baffler type resonator and a magnaflow on the car, and i rememeber when i first installed the resonator before all my upgrader, that the car did lack a bit of ***** uptop afterwards. do you think that all my upgrades have just made it more noticable? I have full fuel system, including new lines and holley Blue Pump. I'm using a Second gen leading coil pack as my ignition, with second gen plugs. efan, and thats about it.

Thanks

 

its you ignition if you havent done anything to it then get some sort of upgrade higher output coils and so on the firts gen ignition tends to crap out at about 6K.

 

I just mentioned in the above post that I have the direct fire second gen coils

 

sounds to me you need a larger fuel pump and fuel pump regulator

 

You absolutely NEED a good fuel pump and FPR to get times any better than stock (give or take a second). The stock fuel pump doesn't even deliver enough fuel to comfortably drive the car with a modded carb alone, let alone a streetport.
When me and Jay bought our Carter fuel pumps, we were absolutely AMAZED at how much quicker our cars were! I'm talking at least a second off of what we had before. No joke.
Ignition is equally important. I recently upgraded to Dlifdis and noticed considerable gains in speed, quickness, and FUEL ECONOMY. Im averaging 24 MPG easy, now.

 

Im curious what size venturies is he using as my bros stock and used 12-A motor with IDA and stock tires run faster than that. Yeah, thats LACR altitude

 

Did you rejet your carb to flow enough fuel at the top end for a street port ? Did you tune it at full throttle under load or just sitting in the garage? Makes a big difference.

 

Man the racing beat exhaust systems that Racing Beat and MazdaTtrix sell suck ***. Don't get me wrong there good for street apps but for someone who every once in a while wants to open the car up and see what it's potential is needs to either run open header, or run the racing beat header and then convert the tail end of the header into 3 inches all the way back with a 3 inch muffler inlet and a 3 inch outlet. That's what I have been running now for about 3-4 yrs a little loud but very responsive, and no ticking or chocking toward top end.

 

+1. Thats what I run and its all it should ever have. Also just because you use a 2nd gen coil and plugs doesnt mean your ignition is good. You need to have a good signal all the way up, and not loose power to the coil through the rpms. You also need a better fuel system.

 

I said i have a Holley blue pump with all new lines, and i use the holley FPR, If my fuel system wasn't suffiecient wouldn't the AFR lean out and raise above 14 at high revs, Like i said the AFRs stay rock solid around 13.6-14.1:1. For wacky racer i'm useing 42 mm Venturies. I'm running 5 PSI fuel pressure, with a return line. as for ignition, i was using DLIDFIS but found using the second gen coils to be smoother, and just as fast.

 

well with a stock port 12a with a 48 IDF, RB exhaust, no emissions, RB flywheel, and RB spark plug wires and EVERYTHING else stock. i ran a 15.3. id say the weather played a big factor. wait till it chills out a little. the car i ran had the stock fuel pump, open diff, shitty tires, bad tune, and had sat for years up until about 6 months prior. it was a colder cripsy night when i ran though. good cool air.

 

hmmm good point, it was hot and humid, and everyone else was complaining of much slower times, I think i'm gonna take off that baffeled resonator, and replace it with a straight pipe, and maybe see if i can get some better ignition and see how that plays out, thanks

 

Grille?

 

Correct, i'm suprised i didn't get flamed by any purists about that little piece

 

Eh. I usually don't flame people about something like that. If it's something that's functional to the car then I don't care what it looks like, it works. Definitely not something I would do to mine but to each their own

 

i know the power band on the stock motor tops off at 6500, i dont really know if that has to do with VE, or just overall design, but i just wanted to put it out as another thing to consider, although i know you have sp, so you will have a higher intake velocity, and volume.