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Re: How good are the P7 engines for drag racing?
[Re: mloboda]
#1212185
04/15/12 03:39 PM
04/15/12 03:39 PM
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Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
Leon441
master
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master
Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
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There is really nothin short in these engines as far as making them a drag race engine. If you want a really aggressive roller cam you need to either convert over or buy a truck or busch engine. The intake valve to exhaust ratio is a little different but, read most of the combos on here they are typically the same as the P7 engines.
Most sportsman drag racers are after big inch engines that don't have to turn real hard. The reason was engines of the past hurt parts when you really zinged on them. They got expensive. These engines basically live forever at high RPM. They don't make the 600 HP of years past but over 800 HP.
Then you get the guy who says the engines have no torque. And look they are running a 408 with nothing heads and no gear ratio. These 408 combos can easily make 600 lbs of torque but run out of air and barely break 600 HP in any adverse air conditions. So when a guy like Bondbob comes out and blast a 5.9 et shifting like a daily driven street car everybody makes excuses for how he misteriously done it. There is no excuse it is simply HP and he hadn't even used it yet. Shifting an engine that only makes 550 torque at 6200. Well he was just starting to see over 700 HP. He had some bad luck and broke a spring now everyone got scared off. Those engines prefer to be shifted at 9,500. That 5.9 ET just turned into at least a 5.50.
I simply want the best of both worlds. An XR or a EEI block and lets pack some stroke under these heads and turn 9,500. SLOW economy and no one buying anything. That is the reason I don't have one and that is the reason others have not either.
Career best 8.02 @ 169 at 3050# and 10" tires small block power.
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Re: How good are the P7 engines for drag racing?
[Re: Leon441]
#1212186
04/15/12 06:05 PM
04/15/12 06:05 PM
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Joined: Feb 2009
Posts: 1,019
Finland
mafo
super stock
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super stock
Joined: Feb 2009
Posts: 1,019
Finland
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a friend of mine have a p7 motor in his valiant, will be ready this summer, I will post up some results later, this is a real streeter with leaf springs and all... I tested one of his heads on my bench and it was one of the best small block heads I have seen, right on par with my cfe w8 s on high lifts and actually a bit better on low lifts  with the short stroke I think the converter is going to be critical but I see no reason why this shouldn t work, I can see 8 sec potential in the right car, and that for less money than I have in the heads 
-65 Valiant,420", all motor,2700#, dot tires, 8,42 @ 160,2
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Re: How good are the P7 engines for drag racing?
[Re: Adrielp]
#1212187
04/15/12 07:36 PM
04/15/12 07:36 PM
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Joined: Jan 2003
Posts: 6,136
Melbourne , Australia
LA360
master
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master
Joined: Jan 2003
Posts: 6,136
Melbourne , Australia
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Quote:
So what are the key differences in the head and engine that make them unable to be used correctly for drag racing? Also, what work is involved to change the engine over to a roller? With the ability to use epoxy, I would think you be able to get the port shape back to whatever you wanted. Also, one would be replacing most of the valvetrain anyway. Also, since there is less meat on the intake port side, has anyone thought of welding the top of the intake ports a certain amount, then re-machining spring seats and rocker stands, you would just longer pushrods after that correct? I figure you could get a .25 to .375 more height in the port.
I really don't get where this misconception that a P7 headed engine won't make a good drag engine, I can only put it down to the fact that the people making these statements know nothing about what goes into a Comp eliminator style engine. There are plenty of SB2.2 and Chevy Splayed valve engines making big power, the P7 deal would be no different.
Leon made some very good points also.
Alan Jones
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Re: How good are the P7 engines for drag racing?
[Re: Adrielp]
#1212188
04/15/12 09:02 PM
04/15/12 09:02 PM
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Joined: Oct 2006
Posts: 247
nc
moeflo
enthusiast
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enthusiast
Joined: Oct 2006
Posts: 247
nc
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Quote:
? With the ability to use epoxy, I would think you be able to get the port shape back to whatever you wanted. Also, one would be replacing most of the valvetrain anyway. Also, since there is less meat on the intake port side, has anyone thought of welding the top of the intake ports a certain amount, then re-machining spring seats and rocker stands, you would just longer pushrods after that correct? I figure you could get a .25 to .375 more height in the port.
I don't think you'd need to weld on these to allow raising the port. It weakens the head, and these heads already have ports high enough for you to be well into the "diminishing-returns" zone. They just don't require much re-engineering unless you are involved in all out ($$$) racing.
Sanborn..you're my hero. Never has so much 1st hand experience with detailed know-how (+ engineering based analysis if required) along with the willingness to share been around for Dodge guys.
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Re: How good are the P7 engines for drag racing?
[Re: moeflo]
#1212189
04/16/12 11:50 AM
04/16/12 11:50 AM
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Joined: Mar 2007
Posts: 572
Shelbyville, TN USA
40ford
mopar addict
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mopar addict
Joined: Mar 2007
Posts: 572
Shelbyville, TN USA
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Moe, good to hear from you! I'm no hero----although I do still have the scars from the arrows in my back---some old wounds go back 30 years or more.
A little more about the P7 heads----We have a set of Ernie Elliot heads, a set of Evernham heads and a set of Davis heads. The Elliot and Evernham heads are close---especially for gas. The Davis heads I was not impressed with---for gas(without a lot of rework). The Elliot and Evernham heads both were subjected to a CNC "lightening" program which removed a lot of material around the intake port. So they are somewhat limited as to future enlarging. The Davis heads didn't have the "lightening" program, so a lot of material remains for enlargement.
We run methanol---which needs different work for best performance. The intake/exhaust flow ratios are different. We chose to use the Evernham heads because they flowed better out of the box and the "lightening" program wasn't as aggressive which allowed more work on the intake runners. After rework, the Evernham (modified for methanol) flowed 407CFM @ .400" and 422CFM @ .800" and didn't stall up to 1.000". These numbers are with the standard 2.185" intake valve with 11/32" stems.
We run a nostalgia FED----so we have self limited ourselves with modifications, money spent, etc. If we had a desire to spend a lot of more money, the Davis heads can have much larger intake runners, but need much larger valves to take advantage of the larger runners. And we limited ourselves to .800" lift valve lift for good spring life. There is a lot of flow in the "non lightened" Davis heads BUT be prepared to spend some money and be prepared to buzz the engine higher. With our current setup, 7.40s are easily attainable----the car is capable of 7.00s but it takes more inches, more head flow and more cam lift. We just don't choose to do it!
There are many different versions of the P7 engine depending on the builder, and the track the engine was designed for. Numerous head programs, different camshaft selections, etc., are all awaiting a buyer of a "obsolete" P7 engine. The engines were designed for use in Nascar and race gas. Drag race applications do require changes especially for a light car like ours. An example for desired drag race changes-----we would really like or lobe separation( have 115 1/2 degrees) but more require a "custom", billet core---with a significant cost. We choose to not bear the extra cost.
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Re: How good are the P7 engines for drag racing?
[Re: 40ford]
#1212190
04/18/12 03:00 PM
04/18/12 03:00 PM
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Joined: Sep 2005
Posts: 769
Europa, Estonia
Georg
super stock
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super stock
Joined: Sep 2005
Posts: 769
Europa, Estonia
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40ford - I sended you mail in pm also this time. Maybe your box is full? Just that my mail is too long to discuss it here
Thanks
Georg
Outlaw Plymouth Valiant
R5/P7 Powered by Liuzzo Racing
COMP Performance Group dealer in Baltic
Premium Performance
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Re: How good are the P7 engines for drag racing?
[Re: 40ford]
#1212191
04/18/12 04:24 PM
04/18/12 04:24 PM
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Joined: Jun 2008
Posts: 577
Arkansas
Adrielp
OP
mopar
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OP
mopar
Joined: Jun 2008
Posts: 577
Arkansas
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Quote:
Moe, good to hear from you! I'm no hero----although I do still have the scars from the arrows in my back---some old wounds go back 30 years or more.
A little more about the P7 heads----We have a set of Ernie Elliot heads, a set of Evernham heads and a set of Davis heads. The Elliot and Evernham heads are close---especially for gas. The Davis heads I was not impressed with---for gas(without a lot of rework). The Elliot and Evernham heads both were subjected to a CNC "lightening" program which removed a lot of material around the intake port. So they are somewhat limited as to future enlarging. The Davis heads didn't have the "lightening" program, so a lot of material remains for enlargement.
We run methanol---which needs different work for best performance. The intake/exhaust flow ratios are different. We chose to use the Evernham heads because they flowed better out of the box and the "lightening" program wasn't as aggressive which allowed more work on the intake runners. After rework, the Evernham (modified for methanol) flowed 407CFM @ .400" and 422CFM @ .800" and didn't stall up to 1.000". These numbers are with the standard 2.185" intake valve with 11/32" stems.
We run a nostalgia FED----so we have self limited ourselves with modifications, money spent, etc. If we had a desire to spend a lot of more money, the Davis heads can have much larger intake runners, but need much larger valves to take advantage of the larger runners. And we limited ourselves to .800" lift valve lift for good spring life. There is a lot of flow in the "non lightened" Davis heads BUT be prepared to spend some money and be prepared to buzz the engine higher. With our current setup, 7.40s are easily attainable----the car is capable of 7.00s but it takes more inches, more head flow and more cam lift. We just don't choose to do it!
There are many different versions of the P7 engine depending on the builder, and the track the engine was designed for. Numerous head programs, different camshaft selections, etc., are all awaiting a buyer of a "obsolete" P7 engine. The engines were designed for use in Nascar and race gas. Drag race applications do require changes especially for a light car like ours. An example for desired drag race changes-----we would really like or lobe separation( have 115 1/2 degrees) but more require a "custom", billet core---with a significant cost. We choose to not bear the extra cost.
Thanks for the info! I think the majority of guys thinking about drag racing these engines would know that they would need to get a camshaft designed to take full advantage of the potential power. How big is the cam core in these engines. I saw a set of rockers arms on line that were 2.0 ratio. Thats a lot of pressure being applied to the camshaft. A bigger cam core might be better assuming there's room for it.
Adriel Paradise
Substation Design Engineer III
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Re: How good are the P7 engines for drag racing?
[Re: Adrielp]
#1212197
04/19/12 01:05 PM
04/19/12 01:05 PM
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Joined: Mar 2007
Posts: 572
Shelbyville, TN USA
40ford
mopar addict
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mopar addict
Joined: Mar 2007
Posts: 572
Shelbyville, TN USA
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A little more on P7 engines. First, please understand what these engines were designed for. They were designed for NASCAR racing only, not drag racing.
In NASCAR, there are three touring series; Cup, Busch and Truck.
The rules are different for each class. The Cup engines are FLAT TAPPET ONLY. That is where the extreme rocker ratios come from(to to 2.1 to 1). On a flat tappet cam, you can use a high ratio rocker and get better area under the lift curve. Also, with flat tappet cams, you use lower pressure springs----the high ratio rockers will last, at least for one race and that is all an engine builder cares about. After the race is over, the rockers go in the trash.
The truck and Busch engines both use roller cams with high spring pressures. You don't see rocker ratios higher than 1.80 to 1. But, the heads and cams are different for the two classes. Busch uses a 390 CFM Holley type carb, thus the cams are smaller and oftentimes the heads are too. The truck engines use 830CFM Holley type carbs and oftentimes the heads are bigger too.
I mention the Holley TYPE carbs because many are not Holley carbs but Titanium billet "lookalikes". They weigh less than two pounds and cost bigs $$$. That is the reason you never see any on the used market and the few you see are dyno carbs. That may change since NASCAR is converting to injection but none of the big $$$ carbs are on the market yet.
Now, lets talk about general cylinder head rules----NASCAR specs valve size(not stem size), valve angles, intake port centerline specs and intake port square inch areas. Most NASCAR engine builders machine away any excess aluminum(weight) around the intake runners---since the size of the runner is spec'd. Therefore for drag racing, there may not be a lot of excess "meat" available around the intake runners. You see a lot of heads with smaller MM size valve stems----these are generally one race valves. Guess what happens to the valves after the race-----trash can! Same with springs, sometimes retainers, titanium shoulder locks, etc. One note----the springs take a specific retainer and titanium shoulder lock. You get into trouble if you don't match the spring to the retainer and the lock.
Now about the cast iron blocks, They are 9.00" deck blocks, same a SB GMs. And, the blocks are big bore(up to 4.185") but short stroke, around 3.25". The main bearing saddles are for a 2.25" Ford type bearing. Only the Elliot aluminum blocks are for a larger 2.50" main bearing. You can easily get a longer stroke crank---all you do is buy a custom billet crank---up to about 3.625" for a 9" deck iron block. And you can bore the blocks larger---but where do you find the deck plates? And the blocks are very hard and last for many, many laps. Our block has thousands of laps on it---still standard size and we have changed pistons four times. We think the iron block can go to about 400" with a reasonable rod length and still run good RPMs.
Since these are purpose built engies, they have no provision for wet sump oiling-----DRY SUMP ONLY!
About out of breath----need coffee!
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Re: How good are the P7 engines for drag racing?
[Re: Oyvind Mopar]
#1212199
04/21/12 10:21 AM
04/21/12 10:21 AM
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Joined: Jan 2003
Posts: 6,136
Melbourne , Australia
LA360
master
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master
Joined: Jan 2003
Posts: 6,136
Melbourne , Australia
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I would be interested to see what one of these titanium carbs looks like, I am sure I am not alone on that one.
I am curious as to how much the flat tappet engines heads are different to the craftsman truck heads. I have a set of Arrington heads sitting in the garage, their sister heads made 846hp with a low 260's @ 0.050" roller. Haven't bothered putting them onto a flow bench as I don't have valves for them.
Alan Jones
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Re: How good are the P7 engines for drag racing?
[Re: 40ford]
#1212201
04/21/12 07:34 PM
04/21/12 07:34 PM
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Joined: Jan 2003
Posts: 6,136
Melbourne , Australia
LA360
master
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master
Joined: Jan 2003
Posts: 6,136
Melbourne , Australia
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Moreso justcurious as to how they machined etc. what step over etc, just being a geeky machinist, lol
Alan Jones
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Re: How good are the P7 engines for drag racing?
[Re: 40ford]
#1212202
04/22/12 11:21 AM
04/22/12 11:21 AM
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Joined: Jan 2010
Posts: 588
Franklin, TN
23T Hemmee
mopar
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mopar
Joined: Jan 2010
Posts: 588
Franklin, TN
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Quote:
How much is a lower center of gravity of four pounds worth?
After seeing what they machined off of the outside of your intake runners to lose weight, it obviously is worth a bunch.....  
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