Eddy Performer RPM or Twisted Wedge heads on 408??

[Black1987Stang]

I know they're pretty small for the motor but how much difference could it be on a 408 stroker from Trickflow Twisted Wedges with port work to Edelbrock Performer RPM heads . I know it's probably like apples to oranges but how much power difference could it be 20-30rwhp? more or less? Big noticeable difference?

Main Mods will be
Custom cam
Trickflow R-series or Trackheat
1.7 rockers
1 3/4 l/t's out to 3 inch exhaust

Thanks

 

[clement]

i can tell you for a fact the OOTB 170cc TFS TW has a larger ACSA and will also have a larger MCSA than the OOTB 170cc Edelbrock inline valve head. there is no way to know the power. throwning around terms like "TFS TW with port work" doesnt mean a whole lot without having a lot of other information. especially when we dont know the specs of the cam that is going to be used. neither of those intakes are going to get a 408 anywhere near its potential. if one of these intakes is to be used, the difference between the two heads mentioned wont matter IMO.

 

[Black1987Stang]

The engine hasn't been fully built yet so the cam hasn't been ground yet either. The cam would be ground to the combo I put on it. I got all the parts because I was going to just build up a 357W but I found a deal on a 408 I couldn't pass up and need to get it going so I'm dealing with what I got. It's just going to be a fun car mainly for the street and track in the summer so I'm not going all out with every part. At this point I have a bulletproof bottom end, then better top end is way down the road.

What's ACSA and MCSA?

 

[clement]

im not talking about going about going all out on every part. im talking about making adjustments to the parts choice so that it will have a nice fat powerband that is desireable on the street as well as the track. you can try to cam it around those intakes, but i doubt the powerband will be very wide. those intakes will be a restriction on a 408. id rethink the intake. once you do that id go with a TFS TW. as far as port work, id rather have an OOTB TFS TW with the correct valves and a valvejob done by someone that knows what they are doing rather then any head with port work done by someone who doesnt have a flow bench and an understanding of how to use it. i would also take the good OOTB TFS TW over the OOTB edelbrock performer head for 408". please dont take this as my choice for a 408 is an OOTB TFS TW. its not, but thats another story.

a custom cam alone is not going to make up for the poor choice of top end hardware you are wanting to use for the piston speed and displacement you are talking about. i understand you have to use what you have, but im not the type thats going to sit here and blow sunshine up your ass. thats just my $.02

ACSA= average cross section area
MCSA= minimum cross section area

 

[Black1987Stang]

I don't like when people say it's gonna be perfect or blow sunshine up my ass so I appreciate the honesty. The motor was originally built by Pat Musi...converted to 4 bolt billet main caps, custom cam with Trickflow high ports, the whole 9 yards, still never ran, but I don't have the 2g's to put down on the heads so I just bought it off a friend as the shortblock since bills and other stuff is more important.

I am now considering a better intake.

As for the heads, I was asking because I have the eddy's I just took off my other car that warped the heads so they got cut I believe .025 thousandths...I'm going to cc them before it goes back on anything. I have TW's with Professional port work, fully done up, problem is they had detonation problems so their 61 cc chambers were enlarged to 65cc....and this shortblock has domed low compression pistons so I need the smallest chamber possible and decking the 65cc down to at least a 58cc could be pushing it deck thickness wise?....and at that point I would still only be at high 8:1 compression so I thought about using the Eddy's because they had much smaller chambers OOTB plus they were even smaller from being decked....just to get me going till I could afford those hi ports or something.

 

[clement]

you can take .100 off the deck of a set of OOTB TFS TWs and still be fine. that would take the chambers down significantly. i know the TEA CNC TWs come as 65cc chambers and can be taken down to 49cc's. so talk to your head guy. id want to know what the dish of the piston cc's. where the deck of the block is, which piston (in terms of C/H) were used, bore size and stroke to calculate compression.

what does your engine builder say?

 

[Black1987Stang]

That's right, I remember my friend that cut my eddy's say they cut heads for racing motors around .100 all the time. As for the engine builder it is me, on this motor the whole shortblock was done by Pat Musi, but I will be swapping the previous cam out for mine and I will be assembling everything else together.

I would need to get the tw's cut a good amount to get the c/h up a bit, but then the whole non tw piston to valve clearance starts to get closer and closer.....but I won't know how much I can cut or can't since I don't know the cam specs yet right?....but using this as an example, since it was setup for a cam with .681 of lift and say mine comes out to .550 then I have say a good .100 to play with right? Not 1.31 since it was relief'd for an inline head and need to take that into consideration...and just an assumption since we don't know the depth of the reliefs. But it all comes down to the cam specs on how much the heads can be cut correct? 'll have the motor this weekend and hopefully the guy will have all the paperwork on the pistons, machine work, etc so I can start doing some real calculations.

 

[5spd GT]

The mean (aka. average) cross section does not mean a whole lot.

I would do a TFS head over the RPM. Tim had a 408 with box stock TFS heads and was running mid to lower 10's.

There are better/larger heads for a 408.

 

[clement]

The mean (aka. average) cross section does not mean a whole lot.

it has its uses.

 

[90lxcoupe]

Both or those heads are way too small. If your building a 408 and want to get serious about making power check these out. I wouldnt go with anything less than a 205cc head, and for the cost of CNC porting you would be crazy not to go that route. Everyone thought my 205's would be too large for my motor, including me, but they are perfect, the car charges hard from 3000 rpms to redline.

Edelbrock 61309 - Edelbrock Glidden 18 Degree Victor Jr. CNC Cylinder Heads - summitracing.com

Trick Flow Specialties TFS-5170T010-C01 - Trick Flow® High Port® Race CNC Cylinder Heads for Small Block Ford - summitracing.com


Trick Flow Specialties TFS-51400010-C02 - Trick Flow® Twisted Wedge® Street/Strip Cylinder Heads for Small Block Ford - summitracing.com

 

[5spd GT]

Be careful in comparing average (mean) cross section.

Think of this this simple example to put things into perspective...

Take a 10" pipe with an opening area of 6" and an exit dimensional area at 2" with a linear taper, it would have a 4" mean cross section.

Now take a 10" pipe with a 4" opening area and a 4" exit area, it would have the same 4" mean cross section.

Yet, they would flow VERY differently with different velocity profiles. Comparing the numbers is fun (I agree), but pretty useless in reality. Then throw in twist, turns, and different runner shapes, along with the actual TOTAL intake runner length which can be 2-3 times the runner length (with their own twist, tunrs, shapes, etc.) of the actual cylinder head, you can see the huge variance that can occur. On top of that, you have to have the real mean runner lengths, not the estimated length to compare accurately.

 

[Black1987Stang]

Well these are the heads that were going on the motor, I don't have what he wants for it but I gave an offer and I'm real close with his friend he knew since he was a little kid so we'll see what happens.

http://i39.photobucket.com/albums/e197/Mercs6/TFSHIGHPORTS001.jpg

http://i39.photobucket.com/albums/e197/Mercs6/TFSHIGHPORTS004.jpg

http://i39.photobucket.com/albums/e197/Mercs6/TFSHIGHPORTS005.jpg

No matter what heads I get I plan on getting them cut to get em up to the 9:1 c/r area....and just need an answer about my last question....Will I need to wait till I get my cam made until I cut them or should I get the cam made and then cut the heads to a safe spot where I wont have p to v problems and suck it up for whatever compression ratio I end up with....? What would you do to get the most possible c/r out of it?

 

[5spd GT]

No matter what heads I get I plan on getting them cut to get em up to the 9:1 c/r area....and just need an answer about my last question....Will I need to wait till I get my cam made until I cut them or should I get the cam made and then cut the heads to a safe spot where I wont have p to v problems and suck it up for whatever compression ratio I end up with....? What would you do to get the most possible c/r out of it?

I would cut the cylinder heads, get the compression ratio figured, then let the camshaft grinder know how much you took off and the compression ratio he will work with.

 

[clement]

Be careful in comparing average (mean) cross section.

Think of this this simple example to put things into perspective...

Take a 10" pipe with an opening area of 6" and an exit dimensional area at 2" with a linear taper, it would have a 4" mean cross section.

Now take a 10" pipe with a 4" opening area and a 4" exit area, it would have the same 4" mean cross section.

Yet, they would flow VERY differently with different velocity profiles. Comparing the numbers is fun (I agree), but pretty useless in reality. Then throw in twist, turns, and different runner shapes, along with the actual TOTAL intake runner length which can be 2-3 times the runner length (with their own twist, tunrs, shapes, etc.) of the actual cylinder head, you can see the huge variance that can occur. On top of that, you have to have the real mean runner lengths, not the estimated length to compare accurately.

that isnt exactly what i was talking about. it can be used to compare cylinder fill on different style heads (that you dont know MCSA because you havent had them in your hands to measure it) if you also know the port length of the head. its a rough calculation, and used properly can give you a good idea of flow per average square inch of port. there are other formulas to calculate target port velocity for a given minimum port cross section. average cross section is just another tool that you have to know how to use. its not the end all be all, and its not meaninless either. i know of several of the top head guys in the country that use it.

 

[5spd GT]

that isnt exactly what i was talking about. it can be used to compare cylinder fill on different style heads (that you dont know MCSA because you havent had them in your hands to measure it) if you also know the port length of the head. its a rough calculation, and used properly can give you a good idea of flow per average square inch of port. there are other formulas to calculate target port velocity for a given minimum port cross section. average cross section is just another tool that you have to know how to use. its not the end all be all, and its not meaninless either. i know of several of the top head guys in the country that use it.

How can you know the average runner length, without having them in your hand as well? The cylinder head runner length has to be measured in the same spot on each cylinder head being compared, and hopefully using the same method.

Yep (highlighted in bold), I have 25+ cylinder heads in a spread sheet with that information in it.

It is very elementary (simple), at best. Just as well, as I am sure you understand, the TOTAL runner length volume/length is important, not just the cylinder head. You also know this as well, but port volume alone is meaningless, right along with mean cross section.

A pitot tube (expensive; measures air speed/velocity at certain flow points) ran on a flow bench is going to give you drastically different numbers for the "velocity profile", even if two "similar heads" (similar Mean CS) are being compared.

10+10/2 = 10 and 5+15/2 = 10. See where I am going? Reminds me of calculating the lobe seperation angles for camshafts. There is an endless amount of possibilities.

I know of several top cylinder head guys that do not use it.

 

[clement]

How can you know the average runner length, without having them in your hand as well?

because there are basically only 3 types of valve layouts for a SBF.

The cylinder head runner length has to be measured in the same spot on each cylinder head being compared, and hopefully using the same method.

see above.

Yep (highlighted in bold), I have 25+ cylinder heads in a spread sheet with that information in it.

It is very elementary (simple), at best. Just as well, as I am sure you understand, the TOTAL runner length volume/length is important, not just the cylinder head.

yes, but the average is generally used only for heads, at least in the circles of people i have talked to.

You also know this as well, but port volume alone is meaningless, right along with mean cross section.

i would agree with the part about volume alone, but for the average enthusiast the mean CS has its place if its not used in a vacuum. you really have to know other variables as well in order to use it.

A pitot tube (expensive; measures air speed/velocity at certain flow points) ran on a flow bench is going to give you drastically different numbers for the "velocity profile", even if two "similar heads" (similar Mean CS) are being compared.

right, because target velocity is determined by the displacement, desired peak rpm and minimum cross section. that doesnt mean that ACSA is useless and ACSA is obviously not applicable for this calculation.

10+10/2 = 10 and 5+15/2 = 10. See where I am going? Reminds me of calculating the lobe seperation angles for camshafts. There is an endless amount of possibilities.

I know of several top cylinder head guys that do not use it.

its a tool. it cant be used in a vacuum and the results of its use have to be looked at with outcomes of other formulas, as well as taking into account factors that cant even be calculated because their are so many variables. its just a guide that is to be used along with others. all in all i think we are in agreement because we are both suggesting the OP use the same head for the application.

 

[Black1987Stang]

Ok so my friend that I was going to get this 408 backed out and decided to keep it, sucks but whatever and I appreciate all the help I got on it. So I'm putting together a 74 blocked 357w with TRW L2456-030 domed pistons and theyre not for TW heads so Im going to get a set of different heads so I can get this thing going before my trans goes. Might be getting a set of Dart alum heads, pics below...I'll have the flow numbers tomorrow

Here's some pics of the runners

http://forums.corral.net/photopost/data/500/medium/Trai_World_heads_001.jpg

http://forums.corral.net/photopost/data/500/medium/Trai_World_heads_003.jpg

http://forums.corral.net/photopost/data/500/medium/Trai_World_heads_002.jpg

they're like 68 cc chambers so it should give me around 10.5-11 compression ratio. only problem is I can only find ONE site with info on these pistons (came in the motor) and I want to get the proper c/r so I can tell the cam grinder. Anybody know where I can find more info on these? I can only find the info on them on flatlanderracing.com.........
TRW # L2456-030 I can post pics if it helps :SNSign: