Can someone explain why stage II heads are not streetable?

[Alky V6]

I calculated the turbine nozzle dia. using 1.28 a/r and 2.5 radius. It came out to be 2.02" dia. The latest calc used 2.00". So that is really close. The 1.28 a/r housing is what I'd start out with.
I was using a 65% eff open turbine housing, so I will do one last calc using the 2.02 nozzle dia. and a 70% eff, pulse (split housing), dual ball bearing turbine housing.

 

[Alky V6]

I ran this calc out to the higher rpm.
Compressor eff fell below 65% at 6500 rpm.
Compressor reserve ran out after 7250 rpm.
BMEP peaking at 599 at 4250 rpm, assuming the intercooler eff % parameter is correct.

 

[Alky V6]

Looks real nice Norb. I would be very careful with the boost ramp up on pump gas if the real world spoolup is even close to what the sim is showing.

 

[norbs]

Thanks Don, but what boost are you using 40 psi? Can we bring this down to something more real like 30 psi, and use your head flow cfm to the stage head cfm and see the potential difference, which cam are you using for the calcs? What are the other lines in this calc your setup?

 

[Alky V6]

Thanks Don, but what boost are you using 40 psi? Can we bring this down to something more real like 30 psi, and use your head flow cfm to the stage head cfm and see the potential difference, which cam are you using for the calcs? What are the other lines in this calc your setup?

The latest calcs were using 40 psi. The calcs were done with the 230 cam. The other lines are my current Stage I setup without nitrous assist. Real world, my setup doesn't spool as well as the graph shows without nitrous assist.

 

[Alky V6]

This is my 2nd option for cam, I will probably use the smaller cam as TK lobes scare me!

DURATION @ .050 INTAKE 234 ROCKER ARM RATIO
VALVE ADJ INTAKE .016 DURATION @ .050 EXHAUST
234 INTAKE 1.70
VALVE ADJ EXHAUST .020 LOBE LIFT INTAKE .4120
EXHAUST 1.65
VALVE LIFT INTAKE .700 LOBE LIFT EXHAUST
.4120
VALVE LIFT EXHAUST .679 LOBE SEPARATION 112.0

DURATION .020 INTAKE C/L
110.0
TAPPET LIFT INTAKE 262

TAPPET LIFT EXHAUST 262

VALVE TIMING .050

VALVE OPEN INTAKE 7

VALVE OPEN EXHAUST 51

VALVE CLOSED INTAKE 47

VALVE CLOSED EXHAUST 3

Bringing this up for ref.

 

[Alky V6]

30 psi boost with a comparison of the 2 cams.
Dark blue and green lines are the 234 cam.
The sim agrees with you about the aggressive lobes of the 234. It came up with a warning asking if I wanted to continue the calc with the lobe lift not matching the duration very well.
The difference in hp at 6500 rpm (around 10 hp) may not be worth running the aggressive cam lobes.

 

[Alky V6]

Doing a comparison using my head flow specs won't show much. I had to modify the head flow specs for my Stage I config to get the sim to match real world performance. The flow numbers I ended up with are very close to Stage II head flow numbers.
It could very possibly turn out that all the numbers that I just gave you (bhp/torque) are low and that I might have to modify the head flow numbers you gave me to get the sim to better match your future real world performance numbers. If that doesn't turn out to be the case, then I can only guess that other specs in my config (cam and manifolding specs) are assisting my small heads in acting like larger heads. Which, by the way, was a very important goal of mine when I first started my Stage I project. Those exhaust headers of mine were not created just for looks. Pressure pulse, resonance wave tuning?

 

[Alky V6]

All these EAP sim numbers are bhp, not rwhp.

 

[Alky V6]

I'm not sure if anyone has realized this yet, but if I was forced to modify my Stage I head flow numbers to get the Stage I config sim results to match real world results, for reasons I can only guess have to do with the fact that I bothered to more carefully match camshaft AND manifolding specifications to the heads, then what does that say about my Stage II config? My Stage II config, which is still only on the drawing board. with only sim results, which haven't been adjusted by real world results yet, also could end up being low compared to real world results?
The sim was not able to compensate for something about my Stage I config. Could that also be true with the Stage II config?

 

[Squid4life]

Ugh... This thread turned from something I could follow to feeling like Rocket Scientist 401 class. (Not a rare instance when following Donnies threads... )

Do they sell "Engine Analzyer Pro for Dummies" books? I looked over the software and it seems very, very detailed. I almost expected it to ask "how tall is your engine builder, and is he left-hand or right-hand dominant". Very detailed...

*Sits back and attempts to absorb*

 

[daves87gn]

Ugh... This thread turned from something I could follow to feeling like Rocket Scientist 401 class. (Not a rare instance when following Donnies threads... )

Do they sell "Engine Analzyer Pro for Dummies" books? I looked over the software and it seems very, very detailed. I almost expected it to ask "how tall is your engine builder, and is he left-hand or right-hand dominant". Very detailed...

*Sits back and attempts to absorb*

i feel the same way, but enjoying the hell out of it, and learning

 

[Squid4life]

again Donnie your 100% right, only difference is i will drive my car to the track and "should" run the numbers the car was built to run.

and when they guy ask me why my street car is slower than your race car i will simply answer

1. i dont have a 91mm turbo
2. i dont have 400 shot of nitrous
3. i dont have spool vavle
4. i dont have a after burner???
5. i dont run methanol
6. i dont have slicks
7. i dont have the spaghetti inside my intake
8. i dont have wheelie bars
9. i dont have a wing
10. i dont have a racecar
11. Donnie probably spent more on his management system then i did on my motor
12. i have less in my whole car then he has under the hood of his

then i will say there are also guys that dont have ^^^^^ but have faster cars so i kinda dont see your point anymore, but thanks for answering the original question

and your "radical" 70's build sounds kinda like what chevy put in my Z/28 from the factory but with a larger carb, 410 gear and 6500 red line

By the way Dave, you are going about this the wrong way...



When you are FASTER THAN DONNIE, you can tell folks who ask, "yeah, Donnie would be much faster is he ran heads like these".

Just razzing you Donnie.

 

[Alky V6]

By the way Dave, you are going about this the wrong way...



When you are FASTER THAN DONNIE, you can tell folks who ask, "yeah, Donnie would be much faster is he ran heads like these".

Just razzing you Donnie.

I'm not taking it as razzing. You're absolutely right.

 

[Squid4life]

If it wasn't so much work and re-engineering, I would absolutely love to see what your combo could do with big heads... With your RPM, turbo, etc... WOW! Think you have traction issues now!?!!?

 

[Alky V6]

Ugh... This thread turned from something I could follow to feeling like Rocket Scientist 401 class. (Not a rare instance when following Donnies threads... )

Do they sell "Engine Analzyer Pro for Dummies" books? I looked over the software and it seems very, very detailed. I almost expected it to ask "how tall is your engine builder, and is he left-hand or right-hand dominant". Very detailed...

*Sits back and attempts to absorb*

When you purchase the software, you also get a manual that details each input parameter and output result. Still, you will have to work with it to get familiar with the software. Like I stated earlier on, it took me months to finalize my Stage I project. It is not something simple that you can quickly plug some numbers into and get good results. I also have a small library of books that I did a lot of my research with while using the EAP to develop the Stage I config. Particularly in the area of matching cam specs and manifolding to head flow characteristics and resonance tuning in an attempt to best make up for shortcomings of the heads. In my case, trying to get the most out of heads using only 1.835" intake and 1.5" exhaust valves. Believe me, I was not prepared for what the real world results would be. I will say, all that studying did pay off.

 

[Alky V6]

If it wasn't so much work and re-engineering, I would absolutely love to see what your combo could do with big heads... With your RPM, turbo, etc... WOW! Think you have traction issues now!?!!?

That's exactly why I'm in no hurry to start the Stage II build. It won't only mean the expense of the modifications to engine components, but would also mean building a chassis to handle it. I don't really have the resources to do that.

 

[Alky V6]

The difference between my original Stage I calculations with the sim, using flow numbers that I received from the person that ported and flowed the M&A heads for me, and the real world results ended up being about 300 bhp.
I have since explained the results I got from the port work Mike did for me and he is really anxious to see those heads again. He told me that those heads he did for me should not be able to do that.

Again, the importance of matching camshaft AND manifolding to the capabilities or lack of capabilities of the heads.

 

[Alky V6]

I should also add that the wrong manifolding can kill all that hard work the head porter did to come up with the most bitchin breathing heads.
If you compare one set of heads with bad manifolding to another set of better breathing heads with bad manifolding, you should see some improvement. But, just think if the right matching system of camshaft, manifolding and heads were being used.

 

[norbs]

Donnie, your basing your head flow numbers in the calcs against real world hp numbers. This also means with stage 2 heads and putting flow numbers in, could also be way off from real world results. It is impossible for and M@A head to flow near 340 cfm with your valve sizes. You are having good results with your heads I do agree.