Bigger valves?

[John B]

what cfm gain do you get going from a +1mm head to a 44/37 head?

[moparzrule]

There's no set gain. Totally depends on what the head it's going on flows! The head also has to be ported to accept the larger valve too. No point in installing the larger seats and not doing the bowl work to compensate.

[BadAssPerformance]

I think his question is more, how much does head A (with +1mm) flow vs. head B (with 44/36.8)?

[John B]

I think his question is more, how much does head A (with +1mm) flow vs. head B (with 44/36.8)?

Yes, that's the question. How more more will a properly ported 44/37 flow than a properly ported +1?

[amoparacer]

Some one with this head put up the flow from your flow sheet. Im sure some one has there flow sheet.

[moparzrule]

Some one with this head put up the flow from your flow sheet. Im sure some one has there flow sheet.

Unless the results are from the same flow bench and within a few hours of each other the info is irrelevant. Flow benches flow different between each one, and even the humidity and temperature affects them as well.

John there is no simple answer to your question. Every casting is different. In the big scheme of things, are you basically asking if it would be worth the money to go to large valves over the +1's Honestly my answer to that question is no. It's only worth it if you are trying to squeak out every last HP out of your engine and also had money you didn't know what to do with. The cost in my opinion does not offset the gain. The +1's with a good port job is the best ''bang for the buck''. The ports in these heads simply cannot be opened enough to flow for the large valves, the coolant jackets are too close to the sides. Sure it helps some, but honestly not as much as it should because the larger valve also shrouds the chamber. Thats another good point actually, are you going to be doing this in a G head or a swirl? That would make a difference too. If the cylinder bore's were larger in these engines it would have made for a whole different world of capabilities for an 8V head on a 4 cylinder. We would have heads flowing like 16 valves no problem if we had a 4'' bore and able to run 2.08/1.65 valves like a small block chevy or something. Heck, even a 3.75'' bore would be a heck of a lot better! Are chambers wouldn't be so shrouded and we could run much larger valves.

[BadAssPerformance]

Unless the results are from the same flow bench and within a few hours of each other the info is irrelevant. Flow benches flow different between each one, and even the humidity and temperature affects them as well.

John there is no simple answer to your question. Every casting is different. In the big scheme of things, are you basically asking if it would be worth the money to go to large valves over the +1's Honestly my answer to that question is no. It's only worth it if you are trying to squeak out every last HP out of your engine and also had money you didn't know what to do with. The cost in my opinion does not offset the gain. The +1's with a good port job is the best ''bang for the buck''. The ports in these heads simply cannot be opened enough to flow for the large valves, the coolant jackets are too close to the sides. Sure it helps some, but honestly not as much as it should because the larger valve also shrouds the chamber. Thats another good point actually, are you going to be doing this in a G head or a swirl? That would make a difference too. If the cylinder bore's were larger in these engines it would have made for a whole different world of capabilities for an 8V head on a 4 cylinder. We would have heads flowing like 16 valves no problem if we had a 4'' bore and able to run 2.08/1.65 valves like a small block chevy or something. Heck, even a 3.75'' bore would be a heck of a lot better! Are chambers wouldn't be so shrouded and we could run much larger valves.

Even the moons gravity and planet alignment in the solor system seems to affect flow numbers for some reason, what you are saying is there is no real improvement? Then why did the IMSA race heads use 44/36.8? So what if you are trying to squeak out every last HP out of your engine and also had money you didn't know what to do with?

Within measurement allowances , how much more do the larger valves flow than +1mm valves on the same identical race port job, same head, swirl or G?

[turbovanman²]

You don't need to install larger seats for +1mm valves.

Steve Menegon got wicked flow numbers from the Swirl head, and I think the most out of anyone.

They can be made to flow, it depends on who is doing it and how much money you want to spend. Another reason I went 16 valve,

Back to our scheduled program,

[moparzrule]

what you are saying is there is no real improvement?

You don't need to install larger seats for +1mm valves.

Where are you guys getting that I said either of those???

I said

the cost does not offset the gain

how you get that I said there's no improvement at all baffles me! I also said +1's are the best bang for the buck(it certainly wouldn't be if you had to install larger seats for them too), that doesn't mean there's no improvement with larger valves, I said just not as much as the improvement from stock to +1's. I have no idea how you guys are getting this stuff out of what I'm writing!!!

If I had to take a stab at numbers, which is I guess what you guys are looking for, ball park figures here would be like a good 20 cfm gain for +1's with corresponding portwork, and large valves like another 10-20 cfm again with the corresponding portwork. Like I said, best bang for the buck is +1's because you can use stock seats.

The IMSA head was a G head I happen to be a fan of G heads over swirl's.

[tvanlant]

Unless the results are from the same flow bench and within a few hours of each other the info is irrelevant. Flow benches flow different between each one, and even the humidity and temperature affects them as well.

John there is no simple answer to your question. Every casting is different. In the big scheme of things, are you basically asking if it would be worth the money to go to large valves over the +1's Honestly my answer to that question is no. It's only worth it if you are trying to squeak out every last HP out of your engine and also had money you didn't know what to do with. The cost in my opinion does not offset the gain. The +1's with a good port job is the best ''bang for the buck''. The ports in these heads simply cannot be opened enough to flow for the large valves, the coolant jackets are too close to the sides. Sure it helps some, but honestly not as much as it should because the larger valve also shrouds the chamber.

There is an easier way to test the flow differences between +1s and 44/37s without having to deal with all of the variables Matt was mentioning.
That is... you do up the +1mm head. Get finished, flow it, then knock the seats out and put the bigger seats/valves in and reflow it after a little blending work. This gives you the result of the valve size on the exact same port of the same casting on similar weather conditions (if you can do all that in a few hours, then it would be same weather conditions too ).
And yes, I have tried it.
The only factor that changes after that is how you would change the port shape/size if you were to originally do the head as a 44/37 head and not a +1mm head.

I agree with Matt that the +1 heads are a better value. I also trust heads using stock seats much more than heads with seats that have been replaced. Especially improper seats are chosen and they overlap.

[BadAssPerformance]

Where are you guys getting that I said either of those???

I said how you get that I said there's no improvement at all baffles me! I also said +1's are the best bang for the buck(it certainly wouldn't be if you had to install larger seats for them too), that doesn't mean there's no improvement with larger valves, I said just not as much as the improvement from stock to +1's. I have no idea how you guys are getting this stuff out of what I'm writing!!!

Maybe when you said it cannot be done?

The ports in these heads simply cannot be opened enough to flow for the large valves,

[minigts]

You also said:

Unless ...results are from the same flow bench and within ...each other the info is irrelevant. Flow benches flow ... humidity and temperature ... as well.

John ...is ...simple .... Every ...is different.

In ...things...you basically ...worth the money to go to large ...
Honestly... no.

It......squeak ...your engine and ...money you ... know

.... The cost ...does not ....

The ... job is the best ... buck....

The...heads simply... open... for ... large ...... jackets ... sides.

Sure ... some... honestly ... should because....

Thats ...good ... ...to be doing this in a ... head ...

That would make a difference too. If ... larger... engines ... would have ... a ...world... 8V....

We ...have heads flowing... no problem if we ... bore and ... run ... like a small ... something.

Heck, even ... a heck of ... better! Are ...we ...much larger ....

I don't know WHAT IT ALL MEANS!!!

[minigts]

I'm joking, btw.

[moparzrule]

Maybe when you said it cannot be done?

If you take what I said in conjunction with the rest of the paragraph, than you would know what I meant. You took my sentence out of context. I said-

The ports in these heads simply cannot be opened enough to flow for the large valves

The ports in the heads cannot be opened up to flow to the potential that 44/37mm valves should be flowing. What I mean is the port is the absolute bottleneck when using those valves. Will they flow more than +1's, yes with proper porting, but are they flowing to the potential they should be? No because the ports won't allow it. You simply cannot open the port up enough to match the size of the valve.

[BadAssPerformance]

OK, now that we're on the same page... so how much more do they flow than the +1mm's in one of the subject heads?

[moparzrule]

From what I've seen (limited experience) about 10 CFM in a well ported swirl and 15-20 in a G head.

[Sloride]

From what I've seen (limited experience) about 10 CFM in a well ported swirl and 15-20 in a G head.

and thats about the difference in the #s johnB and I both posted on the other board.... but as stated the numbers arn't a great comparison do to all the variables....

But its November, the beginning of bench racing season.
Our heads were both flowed at 28" on different benches at different times, by different operators.... my head could have satanic roots ect.

(My Big valve) (JohnB's swirly +1) (JohnB's G +1)

.100 78cfm 73.9 59.4
.200 132 110.92 106.92
.300 168 147.4 154
.400 194 178.4 178
.500 211 198.13 190
.600 216
.700 216

[moparzrule]

(My Big valve) (JohnB's swirly +1) (JohnB's G +1)

.100 78cfm 73.9 59.4
.200 132 110.92 106.92
.300 168 147.4 154
.400 194 178.4 178
.500 211 198.13 190
.600 216
.700 216

Thats interesting. Typically I get larger low lift numbers with my G heads compared to the swirls. Who did the porting?

[Sloride]

My head was done by hp engineering

i think johnB's swirl is a steve m.