[Eagle2000GT]

Got it. 70mm TB good, not much loss with 75mm, 90mm probably bad.

Actually I do understand the basics. I just didn't know which of Accufab columns to use for our 2v motor.

[02'TrueBlue]

Originally Posted by cliffyk I have a can of that in the garage, it may get a tiny bit soft at higher temps until it cures full--though the heat will help it cure. Have you used it before? I ask because it takes at least 2 (and as many as 4) pretty heavy coats to get a deep wrinkle, with 30-45 minutes between coats, and then will take 8-12 hours before you can handle the part without upsetting the finish.. Even after 24 hours it will be a bit soft and in my experience it can take 3 to 4 days before it really toughens up--however once it does it's pretty tough stuff.

Thanks for that info! I do still have the stocker, so maybe I'll just totally replace the part for a few days and give it a few heat cycles till it seems like it's on there real good before I think about putting it back on. Any experience cooking it in a kitchen oven?

[cliffyk]

Originally Posted by 02'TrueBlue Thanks for that info! I do still have the stocker, so maybe I'll just totally replace the part for a few days and give it a few heat cycles till it seems like it's on there real good before I think about putting it back on. Any experience cooking it in a kitchen oven?

I have used a heat gun (an older version of this) to speed up the "wrinkling" with good results--it stinks while doing that, so if you have some sort of SWMBO in your life you may wish to proceed cautiously with the kitchen oven concept.

Even with the heat it still takes a few days for the coating to fully cure...

[02'TrueBlue]

Alright thanks a lot man, today's projects will include brake bleeding, throttle body swapping, finding a heat gun, buying the can, and testing my paint skills lol. I'll let everyone know how it turns out. Thanks again!

[sillyrabbit0420]

Originally Posted by 02'TrueBlue VHT Wrinkle Plus Coatings i was gunna get my hands on a can of this. Think the engine heat will be able to cook it or would I have to stick it in an oven still since its not really attached directly to the engine?

I just sent an AFM Powerpipe and my Vortech discharge tube to Reggie to get powder coated. It turned out fucking awesome, and he had it back to me in just a few days.

[Kevin C]

I'm really just honestly pleased that for once, someone knows how to spell Edelbrock. Not Eldebrock.

[blkfordsedan]

Originally Posted by cliffyk On an n/a engine it is roughly equivalent to manifold vacuum, except that manifold vacuum is an aggregation of the pressure drops of all components of the intake right back to the outside world (plenum, throttle body, intake tube, MAF air filter, air box, and NVH snout). Pressure drop across the TB and upper plenum is a function of engine RPM and throttle setting, which dictates intake air CFM. Assuming for a moment WOT operation (which I am sure is where Accufab ran their tests), then intake CFM = 281in³ / 2 / 1728 * RPM * VE; where VE = volumetric efficiency, always less that 1.0 for n/a, assume 0.9 at best for the 2V engine; or combining the constants, 0.813 * RPM * VE; or 0.0732 * RPM, including VE of 0.9. So, at 6500 RPM the most a 2V could possibly suck in is 0.732 * 6500 = 475 CFM. This is why too large a TB can affect charge velocity and actually cost power at WOT and high revs. With a 75mm TB this reduction is negligible (but you won't gain anything vs. a 70mm unit)--IMHO the BBK 78mm TB/plenum combo is too big for any 2V n/a application.

Good stuff! One thing I would add (and I could be way off base);
It's my understanding that with EFI, where the engine is being fed from a large open plenum, the flow velocity between the plenum chamber and intake valves is the most critical and has the greatest effect. It would be determined by the design of the intake runners & heads, whereas the flow velocity into the plenum chamber (i.e. through the TB & upper plenum elbow) is not near as critical. All it has to do is to fill the penum chamber. Obviously, in a carb application, the air velocity and flow through the venturis is used to meter the fuel and proper carb size is crutial for optimum performance & drivability. In other words, as long as the TB size is within reason for airflow modulation and not restricting the airflow, the velocity through the TB is not of major concern. On the other hand, I can also see where too much of a drop in pressure differential would negatively effect the flow into the plenum chamber. I think this goes along with what you were saying, but if you can expand on this I would welcome the input!

[cliffyk]

Originally Posted by blkfordsedan Good stuff! One thing I would add (and I could be way off base); It's my understanding that with EFI, where the engine is being fed from a large open plenum, the flow velocity between the plenum chamber and intake valves is the most critical and has the greatest effect. It would be determined by the design of the intake runners & heads, whereas the flow velocity into the plenum chamber (i.e. through the TB & upper plenum elbow) is not near as critical. All it has to do is to fill the penum chamber. Obviously, in a carb application, the air velocity and flow through the venturis is used to meter the fuel and proper carb size is crutial for optimum performance & drivability. In other words, as long as the TB size is within reason for airflow modulation and not restricting the airflow, the velocity through the TB is not of major concern. On the other hand, I can also see where too much of a drop in pressure differential would negatively effect the flow into the plenum chamber. I think this goes along with what you were saying, but if you can expand on this I would welcome the input!

Good point, and you are correct that the flow velocity through the TB and upper plenum is of less importance that that in the runners--however it is not of no importance (forgive the double negative) as the air is still being drawn in in pulses and pulses of higher velocity will refill the lower plenum more effectively.

It is the pulsed nature of the intake flow, that air has mass, and that without pressure differential there is no flow, that I find to be most misunderstood by enthusiasts.

[blkfordsedan]

Originally Posted by cliffyk It is the pulsed nature of the intake flow, that air has mass, and that without pressure differential there is no flow, that I find to be most misunderstood by enthusiasts.

IMO, one of the advantages to aftermarket CAI is the smooth interior surfaces of the tubing and the smooth, consistent bends.
I see many people remove the Helmholtz resonators out of the intake tract duct because they think it's only for sound reduction, which in some cases can be true. What they don't realize is that in some cases it is designed & tuned to cancel out specific wave pulses that can actually stall the flow in the tract. I have also heard some "direct" ram air set-ups on EFI applications can actually screw up the wave pulses in the intake tract and cause surging or stalling at certain speeds. I had this happen myself, on a small 4-cyl car. I added a short, straight intake tube between the grill opening and the airbox. The result was serious surging on accelleration at highway speeds.

[cliffyk]

The early Miata's had a Helmholtz box in the intake tube--removing it sucked 7-10HP out of the 3000-3500 rpm range...

[thatkaratekid]

Bringing up an old thread, but to ask a different question. I have the Edelbrock Manifold, Rails, and their Elbow. From reading this info, having a 70 or 75 is good for a n/a car. I will be getting a fully built engine sometime soon, and would like to put the Edelbrock products on the new engine. Once I have it, I would like to spray a 125shot. I love the idea of having the 90MM TB from Edelbrock, and from what I have read, it is kind of pointless.

My questions are if I have a fully built engine with nitrous, could I use the 90MM TB, and would it hurt me in any way? I have a stage 3 Spec Clutch Kit, and people on here have told me many times it is an overkill. Well I have also heard having the 90MM TB is an overkill. I have never had any problems with my clutch, so that being said, even if having the 90MM TB would be an overkill, will this hurt me???

I would also like to have the C&L CAI like he mentioned at the beginning of the thread, just so I can do it Grabber Blue.

[ChamberZer0]

So basically in the essence of all this information, the Plenum/TB combo is worthy for some HP gains?? I read somewhere that the Plenum was basically worthless for any gains as far as HP? Maybe the forum I was reading, they were confused lol..

[99GT35thLE]

I would like to see what would happen on a dyno when installing a 90mm TB on a built engine that can spin to 7000-7500 rpm.

I've seen it posted numerous times that on a built engine the stock intake manifold is a restrictor because it will only flow a certain amount, I forget what that amount is suppose to be.

[blkfordsedan]

Originally Posted by ChamberZer0 So basically in the essence of all this information, the Plenum/TB combo is worthy for some HP gains??

Yes.......very few on a stock motor. But, just like any airflow mods, as other mods are introduced (ported heads, cams, compression, exhaust, etc.) the gain becomes greater. A 70mm or 75mm TB & plenum may only be worth 3-4 HP on a stock motor, but they could be worth 10-12 HP over the stock set-up if you have ported heads, cams & LT headers.

[BakerFX4]

CliffyK just hit this thread with some hardcore shit! wow!

[cliffyk]

The stock upper plenum is the weakest point in the stock intake, if you look at Accufab's flow numbers here you can see that--any aftermarket plenum¹ with the stock 65 mm TB will outflow the stock plenum with a 75 mm TB.

An after market plenum/TB will not make spectacular peak HP gains, however those who dismiss them because of this are displaying their ignorance. What a plenum/TB will do is add a noticeable amount of grunt at WOT in the upper mid-range, and let the engine pull strongly right up to the rev-limiter. For running n/a a 70 mm TB has a theoretical edge over the 75 mm because of higher charge velocities at WOT; however in practice this is not a major issue so if you want a 75 mm TB for bragging rights go for it...


---------------------------------------------
¹ - Any but the C&L which did not do as well as the others with the 65 mm TB--that could very well be an anomaly.

[BakerFX4]

so a 90mm Fox TB will bolt up to the edelbrock elbow? How good of a piece is the edelbrock elbow vs. the 6061 piece?