[Pont428]

JC`s engine wouldnt rev at all! It revs more than the traditional Pontiacs with less CID, so why is that?

[Pont428]

Biggest Engine I can make, McCarty heads over 500 CFM, twin dominator. JC`s record breaking engine sold me. I just think spending all that money on moving the push rod out isnt for me. I would rather have the additional flow and greater port area. I love JC`s engine it is great for his class. Lynn has 3 or 4 engine designs since doing that one.

We are just waiting to find a tall deck block.

[twinturrbo406]

Originally Posted by dci

Pont428, I don't know if we have ever met before. Were are you located?



Don Johnston
DCI MOTORSPORTS INC.
330-850-5050 shop
330-628-3354 cell
Designer of the DCI Tiger Heads and the NEW DCI Ram Air 5 Heads !!!!!

... that's Lynn's brother Steve ... i met him at PRI, he's a very nice guy ...

[tom s]

Steve or Stacy?Tom

[twinturrbo406]

Originally Posted by tom s

Steve or Stacy?Tom

... i thought it was Steve, but you might be right with Stacy ...

[dci]

It's not my style to bash someones idea's and or products especially out in public. So I really have no comment on how or what Lynn's heads are capable of .

I can tell you that my 5 heads do flow very well as cast and respond well to porting. They sound really good on the flow bench and do not back up with a fairly conservative valve size. As for wet flow !! I really don't know what they will do yet. So I cannot spout off or beat on my chest until I have solid evidence of what I did with my port design will work. I have done some computer generated models of the flow path with my port design and that is how I came up with the design I did, but until the rubber hits the road. I am purely speculating. I have built several factory Ram Air 5 engines in my career, and I can tell you that they all liked rpm's even on bigger cube engines. So I knew that I had to increase port speed without sacrificing cfm to improve the factory heads. I have never wet flowed a set of ram air 5 heads (mine or factory), but if the wet flow is bad. You cannot tell by reading the spark plugs. All of the RA 5 engines I have built. When you pull the spark plugs they all look really good even after idling for extended periods. In my experience over my 30 + years of doing this. I have found that if you have fuel dropping out of the air from to much carburetor,poorly ported or designed heads, the wrong intake or anything that allows fuel separation. The spark plugs look like black wet pieces of @#$%, and all of the tuning in the world cannot fix it. So do I think there will be some wet flow issues to deal with? Maybe, but know one will know that until air and fuel pass through the engine. I do know though that you don't need a pushrod tube running through a port to have wet flow issues. I know that for a fact!!!!

I really did not start this thread to start a negative path, but a positive one to inspire and promote advancement with a traditional Pontiac engine. I some times wish I was like the rest of the herd out there, and liked Chevy's or Ford's. Fortunately or unfortunately, I guess it depends on how one looks at it. I have Pontiac blue blood and I cannot help but try to try and improve them. So if you guy's don't mind. Let's get back to the subject matter here.



Don Johnston
DCI MOTORSPORTS INC.
330-850-5050 shop
330-628-3354 cell
Designer of the DCI Tiger Heads and the NEW DCI Ram Air 5 Heads !!!!!

[mike leech]

Very Nice post Don. Professional and classy....Just right

[dci]

I forgot to mention the one experience I had with a wet flow designed cylinder head. I had a customer bring me a 383 SBC that he put the latest and greatest wet flow designed cylinder heads on it. His car consistently ran 10.40's @126 mph with a set of chevy bowtie heads that I ported for him. He done some reading on this new wet flow designed head that was supposed to be better than their competitors heads by 20+ HP (I don't remember the exact HP). So he purchased these heads which had about the same port cc's as what he had on the engine, but a little bigger intake valve. Installed the new heads with no other changes reset the timing back to were it was on the engine originally and ran the car. First thing he said he noticed was the throttle response was a little slower and the drive-ability in the pits was poor. Does his burn out and stages the car and will not come up on the converter like it should. Makes a pass get's his time slip 11.08 @ 120 mph. So he thinks it needs re-jetted for the new heads, makes sense. Pulls a couple of plugs and looks really fat. Jets it down 3 in front and 2 in back. Makes another pass still not happy with the way it feels 11.20's @ 118 mph. Pulls the plugs they are looking better so he thinks well maybe the timing needs retarded a little even though the way the engine was with the old heads it only wanted 28 degree's total. He retards the timing to 26 total makes another pass 11.30's 116 mph. By this time he is think okay I screwed up something loads the car up and gets it back home. Checks for a head gasket not sealing, valve lash, all the things he knew had messed with. Nothing!!! He spent most of the summer trying to get the car the run like it did. Needless to say it never did run the number. He brings me the engine and wants me to freshen it up and tells me the story. When I pulled the heads off the engine the piston tops and combustion chambers were so sooty and still wet that it looked like he was running kerosene or diesel fuel. I tear the heads down and don't see anything way out of whack, but I notice that the short turns have a pretty sharp 90 in them almost a point at the apex. I call the customer tell him that I want to rework the heads before I button the engine up. He gives me the go ahead and I get started. When I put the head on the bench to see were it is at I cannot believe how dirty the port sounds. It's cackling hissing, gurgling the test pressure is jumping about 3-4 inches. The head just does not sound happy at all. I went in and radius ed the short turn blended the bowl and changed a couple of angles on the seat and matched the ports all up and put the engine back together. Long story short I have a very happy and loyal customer now and he picked up another 2 tenths from his original combo and 3 mph (10.20's @ 129). So my one and only experience with wet flow design was not a good one. I'm not saying that it's bad. Just saying it did not work in this situation.



Don Johnston
DCI MOTORSPORTS INC.
330-850-5050 shop
330-628-3354 cell
Designer of the DCI Tiger Heads and the NEW DCI Ram Air 5 Heads !!!!!

[dci]

I don't think bore spacing has as much to do with it now as much as everyone thought a few years back. I think that with the advancements in cylinder heads for SBC especially which have a 4.400 BS. That there are some combos making that or close to it now. I know the Ausie Prostock is 4.500 BS, but that is for packaging purposes for that class. Obviously they have shorter decks so they need a little bigger bore to get the cubic inch, rod to stroke ratio that will work.

Anyone here run or know anyone who is running in NHRA comp eliminator? I know those guy's are around 2.7 + per cube and run all kinds of different engine combos.


Don Johnston
DCI MOTORSPORTS INC.
330-850-5050 shop
330-628-3354 cell
Designer of the DCI Tiger Heads and the NEW DCI Ram Air 5 Heads !!!!!

[J.C.you]

I believe most current bore to stroke ratios in prostock are oversquare to the tune around 1.3 to 1 bore vs: stroke. Using that figure with a Pontiac blocks limitations, if one stretched the bore to 4.5 like we did, that figure would be a 4.5 bore to 3.45 stroke. If one wanted to stay with the mindset of 4.4 max bore, it would be 4.4x3.375.

[BruceWilkie]

Originally Posted by J.C.you

I believe most current bore to stroke ratios in prostock are oversquare to the tune around 1.3 to 1 bore vs: stroke. Using that figure with a Pontiac blocks limitations, if one stretched the bore to 4.5 like we did, that figure would be a 4.5 bore to 3.45 stroke. If one wanted to stay with the mindset of 4.4 max bore, it would be 4.4x3.375.

Put those dimensions in a 301 deck height block so you can run shorter lighter rods and a lighter crank and add smaller bearings while your at it.... 301 deck is 9.143 iirc... thats still a decent size for those who want more stroke... being a factory dimension helps in the fight to get allowed to run against the LS and SB2 and Ford small block stuff... especially if you make the argument that they all stretch their blocks to compete in 400 -460 ci range... We've lived there for years but didnt have the heads we have today... which in the right hands I see no reason why we cant meet or beat their power in that ci range. We have bore advantage over those motors and need to capitalize on it. They dont blink an eye to exploit any advantage they find... we need to do likewise.

When we run 500+ ci we are up against bigger bore motors... if running same ci that gives them an edge we cant match without lengthening our block. That bore space and valve size relationship matters... and it matters more than any piston speed advantage our longer stroke might have to offer.

[Pont428]

Fulper you should denounce your old ways and become a new honest man. Daren has done work for us and Don Kennedy. He is a good man. Lynn was talking low cubic inch engines and Fulper misrepresented it and to Daren like it was 500 inch engines. No big deal unless you are bent on misrepresenting the truth. Turn away from your evil. It under minds our sport.

[Pont428]

Originally Posted by BruceWilkie

Put those dimensions in a 301 deck height block so you can run shorter lighter rods and a lighter crank and add smaller bearings while your at it.... 301 deck is 9.143 iirc... thats still a decent size for those who want more stroke... being a factory dimension helps in the fight to get allowed to run against the LS and SB2 and Ford small block stuff... especially if you make the argument that they all stretch their blocks to compete in 400 -460 ci range... We've lived there for years but didnt have the heads we have today... which in the right hands I see no reason why we cant meet or beat their power in that ci range. We have bore advantage over those motors and need to capitalize on it. They dont blink an eye to exploit any advantage they find... we need to do likewise.

When we run 500+ ci we are up against bigger bore motors... if running same ci that gives them an edge we cant match without lengthening our block. That bore space and valve size relationship matters... and it matters more than any piston speed advantage our longer stroke might have to offer.

The 406 will be 8.900 deck or as close as they can get, 4.40 bore and 3.3 stroke, 2.5 mains, 2 inch rods. Block will be here soon. It will make RPM believe me. Pontiacs have sweet spot in this area. They were all ready to place bets on JCs engine now where are they? The final numbers arent yet in.

[Half-Inch Stud]

Don, seems RA V & RA II share the dry-plug benefits.

[pastry_chef]

Originally Posted by Pont428

Daren thought we were talking 500 inch engines. No big deal unless you are bent on misrepresenting the truth.

Actually funny enough Darin quotes Lynn directly.. LMAO
http://speedtalk.com/forum/viewtopic...&sid=0a1051f0c

Darin Morgan » Mon Jul 03, 2006 3:07 pm

Lynn McCarty wrote:My opinion, this is the head that can produce the most power for 500 cubic inches an above to compete with the BBC Pro Stock engines of today.

---------------------------------------------------

Build what ever size you want, it won't hit remotely close to McCarty's claims!!

If anyone wants to see "misrepresenting" read that entire thread..


Where I live we're getting 10 cm of snow tomorrow!! Does not sound like the west coast of California.

[dci]

What kind of duration @ .050 and .200 does everyone think an engine like this is going to need to get 2.3HP per?


Don Johnston
DCI MOTORSPORTS INC.
330-850-5050 shop
330-628-3354 cell
Designer of the DCI Tiger Heads and the NEW DCI Ram Air 5 Heads !!!!!

[BruceWilkie]

Originally Posted by dci

What kind of duration @ .050 and .200 does everyone think an engine like this is going to need to get 2.3HP per?


Don Johnston
DCI MOTORSPORTS INC.
330-850-5050 shop
330-628-3354 cell
Designer of the DCI Tiger Heads and the NEW DCI Ram Air 5 Heads !!!!!

Sims on this type build suggest open/close rate will have big impact... the more that rate gets toned down the bigger the duration gets and VE decreases... I'd put as much rocker ratio to it as I could... then consider the profile it would "like" vs what could be reasonably attained. My software is currently off loaded til I get a new pc so I cant look to guesstimate.

[dci]

I agree Bruce, The cam lobe profile is going to dictate the power potential and rpm for this type of engine. I think that an asymmetrical lobe will definitely need to be used to be able to control valve acceleration and bounce. Rocker ratio in my opinion is going to need to be 2.0-1 or 2.1-1 because of the traditional Pontiac's cam core limitation. The only problem with that is. The amount of load they will put on the cam and pushrods. Flex in these two areas might be an issue. I think that we can get a 60 mm core in there, but the journal in the back of the block will need to be smaller (50-55mm). Maybe with a little creative cam relocating we could possibly get a 65 mm core to fit. A short deck block will definitely help with the pushrod lengths, but for the cu in we are speculating. The rod to stroke ratio is going to pose a problem with the piston at the bottom of the cylinder bore possibly. That would have to be looked at for sure. I think the longest rod you could use and still be able to have enough room for the ring package would be 5.70"-5.850". If the wrist pin gets below the cylinder it will not live long.

JC, Did you guy's do any spintron testing with your combo?


Chad, If that 349 needed 9600 rpm to make that level of power. What rpm do you speculate a 500 cu in would need? With the assumed optimal csa for this engine of course.



Don Johnston
DCI MOTORSPORTS INC.
330-850-5050 shop
330-628-3354 cell
Designer of the DCI Tiger Heads and the NEW DCI Ram Air 5 Heads !!!!!

[Stan Weiss]

Originally Posted by Chad Speier

It's all about RPM. You not going to achieve big hp/cid unless you have high RPM.

Just had a customer make 2.50 with a 349, at 9600 rpm.

Originally Posted by dci

I agree Bruce, The cam lobe profile is going to dictate the power potential and rpm for this type of engine. I think that an asymmetrical lobe will definitely need to be used to be able to control valve acceleration and bounce. Rocker ratio in my opinion is going to need to be 2.0-1 or 2.1-1 because of the traditional Pontiac's cam core limitation. The only problem with that is. The amount of load they will put on the cam and pushrods. Flex in these two areas might be an issue. I think that we can get a 60 mm core in there, but the journal in the back of the block will need to be smaller (50-55mm). Maybe with a little creative cam relocating we could possibly get a 65 mm core to fit. A short deck block will definitely help with the pushrod lengths, but for the cu in we are speculating. The rod to stroke ratio is going to pose a problem with the piston at the bottom of the cylinder bore possibly. That would have to be looked at for sure. I think the longest rod you could use and still be able to have enough room for the ring package would be 5.70"-5.850". If the wrist pin gets below the cylinder it will not live long.

JC, Did you guy's do any spintron testing with your combo?


Chad, If that 349 needed 9600 rpm to make that level of power. What rpm do you speculate a 500 cu in would need? With the assumed optimal csa for this engine of course.



Don Johnston
DCI MOTORSPORTS INC.
330-850-5050 shop
330-628-3354 cell
Designer of the DCI Tiger Heads and the NEW DCI Ram Air 5 Heads !!!!!

HP is about mass air flow / fuel, or you can think about it as VE and power cycles. Lets take a 499 ci engine, bore = 4.44", stroke = 4.03" @ 125% VE and 9600 RPM it will have around 7938 lbs / hr mass air flow. At 8600 RPM to get the same mass air flow the engine would need just about 136% VE.

Stan

[pastry_chef]

Originally Posted by dci

Chad, If that 349 needed 9600 rpm to make that level of power. What rpm do you speculate a 500 cu in would need? With the assumed optimal csa for this engine of course.

If the power level goal is 2.50 HP/cu.in, at the same efficiency (MEP) a larger engine would need the same RPM.

In theory, its more difficult to obtain the same efficiency with larger displacement.
If less efficient, then you would need to spin to a higher RPM.

Gives insight as to how challenging it really is!!!