Accel LTRs - Extrude Hone Them Or Not?

[bradvette]

I just received an Accel SR manifold, Accel LTRs, stock plenum and 52mm TB from another forum member, all ported & matched as an entire working unit by LPE. The workmanship looks very good, and the condition of everything is excellent.

The aluminum cast Accel runners are substantial and look like good quality.
However, the insides of the runner area appears and feels to be somewhat "porous". Compared to a set of AS&Ms, I would assume this would cut down on air velocity to some degree....but how much I have no idea. Would this matter very much for street use?

I also have a set of AS&M runners, but they don't quite match up with the SR base near as well as the Accel runners do (for the obvious reason).

I would think that the negative impact on airflow velocity due to the apparent mismatch of the AS&Ms would outweigh the "porousness" of the Accel runners. Am I right, or out in left field? I was going to use the AS&Ms, but after fitting them on the base I'm having second thoughts.

So I'm left with figuring out whether to go with the AS&Ms, the Accel LTRs as is, or go to the EXTRA expense of having them extrude honed at a cost of $215 (by Extrudehone.com, not many people do this service). Aside from making the runners very smooth, this job would also remove a little material
and make them flow slightly better than AS&Ms.

What advice does anyone have?
On a side note, the Accels are 1" shorter than AS&Ms. My guess is that torque would generally be about the same, but horsepower would be a bit better in the mid and upper RPM ranges for the Accel runners.

 

[-=Jeff=-]

I honestly would use the AS&M runners. I think they are great. I don't know if having the runer end smaller then the Base opening will hurt too much.

I personally never cared for the Cast Accel Runnners

 

[Ken]

If you're building a serious powerplant, and maybe even boost it with a supercharger or something, extrude honing might be worth it, but for a street-driven everyday driver with just a little punch, it's probably overkill. Spend the money on something else for the engine.

 

[Mad-Mic]

If you're building a serious powerplant, and maybe even boost it with a supercharger or something, extrude honing might be worth it, but for a street-driven everyday driver with just a little punch, it's probably overkill. Spend the money on something else for the engine.

yeah i agree here. actually i'll add a bit more...

when you extrude hone an intake part from a porous rough surface to a smooth one isn't the way to make more HP althought the car may flow more CFM. you actually want a rough surface on the intake side of things. even on the intake port of the heads. the reason is because the fuel will not mix with the air properly to give peak burn in the combustion chamber. with the rougher surface the air actually swirls like the "Tornado" gizmo that is out. this in return helps the fuel atomize with the air and burn more clean and makes more HP. don't spend your money on the "Tornado" either :L i was using that as a reference

 

[bradvette]

Thanks for the replies, thats very interesting. Why are AS&M runners so popular, yes they flow like 260cfm (I guess) and the Accels flow at something like 242cfm, so the flow difference here wont make any real difference in performance results? I wonder why theres the big fuss about the AS&M being so smooth and how great this is. It made me wonder since the Accels seem puposefully rough, so this is a completely different approach. So the Accels are actually better units? I'm confused a bit here. I've heard that the rougher Accels would slow down air" vs. the AS&Ms, but if you're saying this isn't the issue and the rough feature of the Accels is actually a superior engineering feature, thats great news. Its weird though, I've always been under the impression that you want smooth flowing runners, not rough. When I talked to LPE, they told me that porting of the runners is expected, lots of folks do it. ?????? Any more input?

 

[bradvette]

Thanks for the replies, thats very interesting. Why are AS&M runners so popular, yes they flow like 260cfm (I guess) and the Accels flow at something like 242cfm, so the flow difference here wont make any real difference in performance results? I wonder why theres the big fuss about the AS&M being so smooth and how great this is. It made me wonder since the Accels seem puposefully rough, so this is a completely different approach. So the Accels are actually better units? I'm confused a bit here. I've heard that the rougher Accels would slow down air" vs. the AS&Ms, but if you're saying this isn't the issue and the rough feature of the Accels is actually a superior engineering feature, thats great news. Its weird though, I've always been under the impression that you want smooth flowing runners, not rough. When I talked to LPE, they told me that porting of the runners is expected, lots of folks do it. ?????? Any more input?

By the way, I'm having heads and cam installed as well. Does this change things?

 

[Ken]

Okay, seeing as to how fuel ghas entered the picture (as it should because it plays an important part in the flow through the intake and heads), are y'all familiar with Superflow's new Wet Flow unit?

WHAT HAPPENS WHEN YOU ADD FUEL?

Now you can answer this question by flow testing with water and dye. SuperFlow’s WFB-1500 attaches to your existing flowbench and allows you to simulate fuel behavior inside the combustion chamber. Quick and easy to set up, the WFB- 1500 will attach to any SuperFlow Flowbench that has a high-output exhaust mode (SF-300, SF-600 and SF-1020 ProBench). Now, it’s been proven that you can have good dry flow numbers, but poor wet flow behavior and sub-optimum power and torque. The WFB-1500 will show you when and where you have low velocity, poor swirl, no tumble, etc. You'll see where the fuel is pooling and when it falls from suspension.

The WFB includes the Control Unit, Slider Plate, Master Deck Plate and Spray Bar and finally the recovery canister. Everything you need to start wet flow testing once you have the flowbench.

I saw them demonstrate this unit recently on a television show, but now I cannot remember what it was. Probably Popular Hot Rodding Televison. :cool

_ken

 

[Mad-Mic]

Brad-

i'm not saying the Accel is the better of the 2. you have to weight the consequences of 260 cfm flow to 242 cfm flow. flow is flow there that is the bottom line BUT to go faster you want what Ken posted which is swirling of the air. a engine is an air pump it's still going to pump the proper CFM what it is pulling in regardless of a rough surface. rule of thumb is intake rough exhaust smooth. again like Ken posted about the "Dry" "Wet" system.

Porting the the TPI is not necessarly going to flow alot more. it's just going to flow more freely. a typical port work on a TPI unit is siamesing the plenum, runners, and lower intake 1"-2" back and typically 1" across the tube itself. this allows the air to bridge the bolt on peices smoothly with less restriction but the rougher edges will let it get good turbulance to atomize with the fuel better. if you look at pictures of ported siamesed setup with the V's cut down the tube, the air actually bounces into itself through out the TPI system. also port matching is done. both faces of the pieces getting bolted together will match up perfectly with no lips.

my suggestion would be if your not porting the TPI use the accels. if you are porting it go with AS&M runners and you will be happy. the 1 extra inch on the runner length will allow more torque but less top end pull. with a good cam you should be able to pull in the 5700 rpm range before it drops off.

Thanks for the replies, thats very interesting. Why are AS&M runners so popular, yes they flow like 260cfm (I guess) and the Accels flow at something like 242cfm, so the flow difference here wont make any real difference in performance results? I wonder why theres the big fuss about the AS&M being so smooth and how great this is. It made me wonder since the Accels seem puposefully rough, so this is a completely different approach. So the Accels are actually better units? I'm confused a bit here. I've heard that the rougher Accels would slow down air" vs. the AS&Ms, but if you're saying this isn't the issue and the rough feature of the Accels is actually a superior engineering feature, thats great news. Its weird though, I've always been under the impression that you want smooth flowing runners, not rough. When I talked to LPE, they told me that porting of the runners is expected, lots of folks do it. ?????? Any more input?

By the way, I'm having heads and cam installed as well. Does this change things?

 

[bradvette]

Mad-Mic, good points and seems quite logical. All the TPI parts were ported together and matched as a working unit. The problem with the AS&Ms is that there is about a 1/8" lip on the runners when mated up to the Accel base (I bolted them on and looked in with a flashlight). I just can't use the AS&Ms like this.

I think an extrude hone job does leave some roughness. It would reduce the extra rougness in the Accels and leave a more desirable condition (I think). As for the 242 cfm vs. 260 cfm (AS&M), some material is taken away and I think the end result is an even higher flow rate than AS&Ms. I'm getting everything from absolutely yes to absolutely no, in terms of getting them extruded.

The AS&Ms are VERY smooth. If roughness is more desirable, then I don't understand why these would be engineered this way.

By the way, there's another difference with the Accels....they are actually about 1/2" shorter than stock runners. AS&Ms are about 1/2" longer than stock runners.

 

[WhalePirot]

1) LPE told me not to bother with extrude honing my SR setup.
2) a friend had EXCELLENT results with the SR base and AS&M runners, from a stock plenum on his 406.

I agree with Ken and Mad, otherwise. Spend your dough where it will pay off.
I'd match the ports and be done with it.

 

[bossvette]

I read somewhere when I was doing my TPI that the smoothness doesnt mean much as the tpi is a "dry" system meaning the fuel is not added until the air charge is at the valve.

 

[SurfnSun]

I have to respectfully disagree here.

Extruding will provide very positive results. The extruded Accel runner will flow 278cfm! Considerably more than the other. Remember your motor is an air pump

Now in addition to flowing more air the extruded runner will flow more air FASTER which will make more torque. Having a rough cast surface will cause turbulance in the airflow hindering power, as said this is a dry intake.

Go get a TPIS catalog. I haven't seen one in a few years, but in the back they compare the TPIS/ASM runner to the Accel cast runner. They make a point below the dyno to talk about the benefits of an extruded runner, which the TPIS is. It has a higher hp reading at a higher rpm.

I have a set of ASM runners, I really wish Id bought the Accels instead. You can get them cheaper and they have more flow potential.

 

[militant_x]

Yes its a "dry" system... so the air swirling doesn’t help with the fuel mixing???? I don’t think so. See if the air is swirling before the fuel is added, shouldn’t it still be spinning at the point where gas is added and therefore help? Now some would argue that you are lowering the velocity of the air charge with this rough swirling air. However wouldn’t smoothing it out or therefore enlarging the bore of the runners slow down the air? A larger bore means slower air. Remember basic physics (now this assumes an ideal fluid which is ideally incompressible) where Area*Velocity = a constant. so increase area, lower velocity. Since this can be argued both ways, how about some dyno numbers?

later,
-chris

 

[bradvette]

1) LPE told me not to bother with extrude honing my SR setup.
2) a friend had EXCELLENT results with the SR base and AS&M runners, from a stock plenum on his 406.

I agree with Ken and Mad, otherwise. Spend your dough where it will pay off.
I'd match the ports and be done with it.

After final analysis, I'm going to leave the Accel runners as is. I need that $215 for better use.
Thanks for everyone's input

 

[SurfnSun]

Yes its a "dry" system... so the air swirling doesn’t help with the fuel mixing???? I don’t think so. See if the air is swirling before the fuel is added, shouldn’t it still be spinning at the point where gas is added and therefore help? Now some would argue that you are lowering the velocity of the air charge with this rough swirling air. However wouldn’t smoothing it out or therefore enlarging the bore of the runners slow down the air? A larger bore means slower air. Remember basic physics (now this assumes an ideal fluid which is ideally incompressible) where Area*Velocity = a constant. so increase area, lower velocity. Since this can be argued both ways, how about some dyno numbers?

later,
-chris

The extrude hone process doesn't leave a "glass like" surface. It leaves very fine lines in the metal going the same direction as the flow of the air. Rough cast aluminum doesn't cause uniform swirling, turbulance slows down air flow.

By your example of larger area = slower flow we should all be putting smaller runners on our cars, not larger ones. The factory runners were too small to begin with. Your statement is true in the fact that a stock 350 doesn't need a 58mm throttle body, but in the case of TPI runners they don't make them large enough to have a negative affect on airflow. Remember the higher hp TPIS/ASM runners are already extruded. They just don't have the "meat" that the Accel runners do, which is why Extruding the Accels has such a positive impact. You get small port with faster air flow.

Bottom line if you want max power...go with Extrude Hone but it is pricey.