Hello from Germany

[Max Power]

I think that this is the place for very good engine advice.

I have a 351W with a roller cam and ported Performer RPM heads that makes 355 rwhp behind a c6 tranny.

Here are the specs. The heads originally had 170 cc intake runners but after porting, they have either 190 or 195. I don’t remember exactly. they also upgraded the valves to 2.02 on the intake

My heads flow this

lift. intake. exhaust
100. 79. 61
200. 162. 121
300. 180. 168
400. 241 178
500. 264. 196
600. 275. 205

My current cam is a hydraulic roller (std base circle) with 236/240 dur at .050 and 540 of lift on the intake and 560 on the exhaust on a 108 LSA

I have an air gap intake, wide ratio gearing, 3.73 rear gears and a 3000 stall converter.

so I am now ready to stroke to a 408. I can either get new heads or electric power steering but not both. I NEED the power steering so I am going to keep my current heads for now. I have seen that enginefactory.com sells a 475 hp 408W using performer rpm heads (the 190 cc intake runner version) and an off the shelf comp cams XE roller.

Comp has suggested a cam for me to use in this set up with the following specs.

hyd. roller with 242/248 dur at .050 with 584/579 lift on a 108 lsa.

can anybody help me understand what the curve would look like? I don’t want a car that is a dyno queen that makes peak hp at a high rpm. I want something like the 408 that engine masters built with the 165 afrs that had tons of torque across the board. I am more of a bottom of the page than a top of the page guy.

If I can get closer to 400 hp at the wheels than I am now, I would be thrilled. Maybe better heads when the money allows but not in the cards for now. Can you guys opine what you think the power curve on a 408 with these heads and cam might look like? thanks.

[6TNCRZY]

For what you want, your current heads should be ok. I would recommend a cam with maybe 10 degrees less duration than Comps recommendation if you are looking for super mid-range torque that still pull to 6000 RPM, similar to the Engine Masters build.

[olddog]

Personally I think your heads are decent heads. I also think your existing cam for what you want is better than what comp is telling you to buy, but then they wouldn't sell a cam. Comp cams are well tested on SB Chevy and then they assume it will do the same thing in a SB Ford. The numbers they never tell you is what is going on in the ramp portion (opening and closing), of the lobes, which is the majority of the time that the valve is open. You can change the ramps on lobes and have two cams with the exact same duration, lift, and LSA, with totally different performance.

Contact Blykins and have him set you up with a cam. I think you would be very pleased.

[olddog]

Originally Posted by Max Power

I have a 351W with a roller cam and ported Performer RPM heads that makes 355 rwhp behind a c6 tranny.

So I am now ready to stroke to a 408.

Excuse my using torque in ft-lb rather than N-M. I just don't think in the superior metric units.

If you change nothing other than the stroke. Same intake, heads, cam, headers, etc., your engines torque curve will shift to 351/408 rpm from the present rpm. Your engine will make the same torque only the rpms will be lower when that happens.

for example:
351 rpm -- torque -- 408 rpm
1000 ------ 350 ----- 860
2000 ------ 375 ----- 1720
3000 ------ 400 ----- 2580
4000 ------ 425 ----- 3440
5000 ------ 400 ----- 4300
6000 ------ 375 ----- 5160

If you had a dyno pull chart on your engine it would be helpful. The question is where does the torque start dropping off faster than the rpm is rising (definition of peak hp). The next question is why is the torque dropping rapidly. If it is because the springs are no longer keeping the valves in control at higher rpm, then your stroker will make more Hp (Kw), as it will continue to make more torque up to that rpm. This is true in theory from an air flow point of view. In reality the stroker will make a bit more torque everywhere as the torque curve will shift up a bit from the stroke increase. However this will give you an idea of how your cam would perform.

[Max Power]

Originally Posted by olddog

Excuse my using torque in ft-lb rather than N-M. I just don't think in the superior metric units.

If you change nothing other than the stroke. Same intake, heads, cam, headers, etc., your engines torque curve will shift to 351/408 rpm from the present rpm. Your engine will make the same torque only the rpms will be lower when that happens.

for example:
351 rpm -- torque -- 408 rpm
1000 ------ 350 ----- 860
2000 ------ 375 ----- 1720
3000 ------ 400 ----- 2580
4000 ------ 425 ----- 3440
5000 ------ 400 ----- 4300
6000 ------ 375 ----- 5160

If you had a dyno pull chart on your engine it would be helpful. The question is where does the torque start dropping off faster than the rpm is rising (definition of peak hp). The next question is why is the torque dropping rapidly. If it is because the springs are no longer keeping the valves in control at higher rpm, then your stroker will make more Hp (Kw), as it will continue to make more torque up to that rpm. This is true in theory from an air flow point of view. In reality the stroker will make a bit more torque everywhere as the torque curve will shift up a bit from the stroke increase. However this will give you an idea of how your cam would perform.

Thanks for the reply.

re: metric vs. standard, there are two kinds of countries: those that use the metric system and those that have landed on the moon.

I am an American stranded in europe for the moment so I understand and prefer the standard system.

Here is a dyno pull. I made peak power at nearly 6600+ rpm, which is more rpm than I was ever hoping to spin this motor. the engine masters 408w using the afr 165 heads made 471 hp at 5400 rpm and 515 ft lbs at 3900 rpm. the cam they used was rather small at 218 / 224 dur at .050 and had 513 of lift. What cam could I use that would make my peak power at or below 6200 rpm?

[cycleguy55]

Originally Posted by Max Power

I think that this is the place for very good engine advice.

I have a 351W with a roller cam and ported Performer RPM heads that makes 355 rwhp behind a c6 tranny.

Here are the specs. The heads originally had 170 cc intake runners but after porting, they have either 190 or 195. I don’t remember exactly. they also upgraded the valves to 2.02 on the intake

My heads flow this

lift. intake. exhaust
100. 79. 61
200. 162. 121
300. 180. 168
400. 241 178
500. 264. 196
600. 275. 205

My current cam is a hydraulic roller (std base circle) with 236/240 dur at .050 and 540 of lift on the intake and 560 on the exhaust on a 108 LSA

I have an air gap intake, wide ratio gearing, 3.73 rear gears and a 3000 stall converter.

so I am now ready to stroke to a 408. I can either get new heads or electric power steering but not both. I NEED the power steering so I am going to keep my current heads for now. I have seen that enginefactory.com sells a 475 hp 408W using performer rpm heads (the 190 cc intake runner version) and an off the shelf comp cams XE roller.

Comp has suggested a cam for me to use in this set up with the following specs.

hyd. roller with 242/248 dur at .050 with 584/579 lift on a 108 lsa.

can anybody help me understand what the curve would look like? I don’t want a car that is a dyno queen that makes peak hp at a high rpm. I want something like the 408 that engine masters built with the 165 afrs that had tons of torque across the board. I am more of a bottom of the page than a top of the page guy.

If I can get closer to 400 hp at the wheels than I am now, I would be thrilled. Maybe better heads when the money allows but not in the cards for now. Can you guys opine what you think the power curve on a 408 with these heads and cam might look like? thanks.

You currently have 1.011 RWHP/cu in. All things being equal, increasing your displacement to 408 CID will give you 412.6 RWHP. All things aren't equal, of course, but even with your existing heads and cam you'll be very close to 400 RWHP. If that's not sufficient you can easily change cam and/or heads at a later date, as long as you have sufficient valve to piston clearance - which you should probably check and measure when putting in the stroker kit.

As noted by olddog your torque curve will shift to a lower RPM, so it seems you may well meet both torque and RWHP goals merely by increasing displacement. Go ahead with the power steering.

[Max Power]

Originally Posted by cycleguy55

You currently have 1.011 RWHP/cu in. All things being equal, increasing your displacement to 408 CID will give you 412.6 RWHP. All things aren't equal, of course, but even with your existing heads and cam you'll be very close to 400 RWHP. If that's not sufficient you can easily change cam and/or heads at a later date, as long as you have sufficient valve to piston clearance - which you should probably check and measure when putting in the stroker kit.

As noted by olddog your torque curve will shift to a lower RPM, so it seems you may well meet both torque and RWHP goals merely by increasing displacement. Go ahead with the power steering.

thanks for the tips. I guess I could up the stroke and see how scary the car is after and then decide whether to get a new cam.

[olddog]

Based on what I wrote earlier, just stroking your engine would give you a peak hp at 5700 rpm. That said, is your engine peaking at 6600 because you are starting to loose control of the valves? Looking at your dyno chart, I am puzzled at the rather steep drop in torque starting around 5300 rpm. I would have expected a more gradual drop off in the beginning. So I am not enough of an expert here. I would advise a good valve train for any engine. Good roller rockers and new valve springs for sure. I suspect your cam would make more torque to a high rpm with better springs, therefore after stroking the engine I think it will peak above 5700 rpm. I cannot be sure though. Let's see what some others think.

Again I would recommend contacting BLYKINS. I think he could set you up with a better cam than you have and a better cam than comp will recommend. I believe he uses Comp and specs the lobes himself. He most likely can purchase your parts and ship them to you for about the same money. He builds a lot of engines and does it for a living.

[Max Power]

Originally Posted by olddog

Based on what I wrote earlier, just stroking your engine would give you a peak hp at 5700 rpm. That said, is your engine peaking at 6600 because you are starting to loose control of the valves? Looking at your dyno chart, I am puzzled at the rather steep drop in torque starting around 5300 rpm. I would have expected a more gradual drop off in the beginning. So I am not enough of an expert here. I would advise a good valve train for any engine. Good roller rockers and new valve springs for sure. I suspect your cam would make more torque to a high rpm with better springs, therefore after stroking the engine I think it will peak above 5700 rpm. I cannot be sure though. Let's see what some others think.

Again I would recommend contacting BLYKINS. I think he could set you up with a better cam than you have and a better cam than comp will recommend. I believe he uses Comp and specs the lobes himself. He most likely can purchase your parts and ship them to you for about the same money. He builds a lot of engines and does it for a living.

thanks for the reply

the heads were ported by Ford Performance Solutions in Kali. Troy also ground the cam based on the head flow post porting. He installed the springs and my mechanic in the NL double checked the springs to make sure they were correct. I will contact Herr Lykins for his suggestion on what cam to grind.

at the end of the day, the fact that I am making 355 hp at the rear wheels behind a C6 tranny means I am making some pretty good power at the crank for a 351W.

All things being equal, should I expect to see a power bump by upping the CIs on this engine, keeping the cam, heads, and intake the same? I saw an episode of engine masters where they put the same heads, intake, and cam from a 350 on a stroker and it only gained 10 hp. Was that anamoly?

[cycleguy55]

Originally Posted by Max Power

I saw an episode of engine masters where they put the same heads, intake, and cam from a 350 on a stroker and it only gained 10 hp. Was that anamoly?

There's not enough information about the state of those heads, intake, and cam to be able to respond in any meaningful way. If they were "the weak link in the chain" they would certainly restrict any gains from stroking the engine.

OTOH, if your heads, intake, and cam have untapped potential you can see significant gains from stroking. Brent Lykins or another quality engine builder is in a far better position to assess that than I am.

Edit: I'm no engine building expert, but that dyno chart tells me your heads, intake and cam are all supporting high RPM breathing. Conclusion: That engine would likely benefit from more stroke.

[olddog]

As said by cycleguy55, if the heads are limiting the power of an engine, stroking the engine gives no gain in power and causes the torque to happen at the lower rpm by the ratio of the displacement change, as I stated earlier.

If the displacement you have and the cam are pulling in all the air of the displacement or more (100 - 100+ efficiency), then stroking the engine will give a huge hp and torque gain.

Your heads are likely somewhere between the two. If I am correct the dyno sheet of your engine has 440 ft-lb peak torque at wheels, which should be in the range of 525 at the crank. That is likely over 100 efficiency with torque being 1.5 times the displacement. So I think the porting on your heads is very good, and likely would do better with a stroker.

AFR are top notch heads, but yours could be as good or better depending on the port work.

[Gaz64]

I was puzzled as to why the two curves don't cross at 5252 rpm, then I realised the the scales are HP and Newton metres.

What dyno operator uses HP (imperial), and Nm (metric).

So you have 441 Nm, not 441 Ft/lbs. 441Nm = 325 Ft/lbs.

So at 5252 rpm, you have about 325 HP, before you then go onto 354 Hp at 6600 rpm.

[Max Power]

Originally Posted by olddog

As said by cycleguy55, if the heads are limiting the power of an engine, stroking the engine gives no gain in power and causes the torque to happen at the lower rpm by the ratio of the displacement change, as I stated earlier.

If the displacement you have and the cam are pulling in all the air of the displacement or more (100 - 100+ efficiency), then stroking the engine will give a huge hp and torque gain.

Your heads are likely somewhere between the two. If I am correct the dyno sheet of your engine has 440 ft-lb peak torque at wheels, which should be in the range of 525 at the crank. That is likely over 100 efficiency with torque being 1.5 times the displacement. So I think the porting on your heads is very good, and likely would do better with a stroker.

AFR are top notch heads, but yours could be as good or better depending on the port work.

re: the heads, I am stuck with them. The TUV made a notation on my registration what engine components I have and I cannot change these notated items out without going through a lengthy and expensive approval process. Sometimes, they even note the size of the the tires on your registration and you cannot change tire or wheel sizes. The police really come down hard on unapproved changes. They like to park outside US Army bases and pull soldiers over and hassle them for unapproved mods.

I don’t think these heads are too much of a limiting factor. they should be capable of nice power with the right cam. they flow more than AFR 165s but slightly less than AFR 185s. Engine masters put afr 165s on a 408W and a small cam it made 471 hp and 515 ft/lbs, all at 5500 rpm or less. I would like to replicate this kind of performance.

THis crate makes 475 hp with the same heads and intake only mine have been ported to flow 20 cfm more at .600 of lift so I should be able to replicate this motor and do even better. I just don’t know what cam they use. It is funny. For their 383 chevy engines, they list the head p/n and the comp cams grind # but they wont tell me what grind they are using on the cam

https://enginefactory.com/ford-perfo...s/408w-475-hp/

[twobjshelbys]

Is that dyno chart really 8+ years old?

No matter how you cut it. The shape of both of those curves says something is wrong.

[Max Power]

Originally Posted by twobjshelbys

Is that dyno chart really 8+ years old?

No matter how you cut it. The shape of both of those curves says something is wrong.

yes. the last 4th of July at Bamberg before the base closed. although the dyno shows the power curve is very steep, I can leave a 60 ft tire mark from a rolling start and it accelerates like a bat out of hell. I am thinking of stroking and using the 34-426-8 comp cam and see what happens.

I am stuck with edelbrock heads for two reasons. First, they are noted on my car registration and I can either up to vic. jr heads or get the electric power steering. I prefer the power steering for the time being.

[6TNCRZY]

I think the air gap intake for 351 Engines is the "choke point" for your engine. With a 3000 stall converter you may want to change to a Vic Jr manifold, it should be good for 25+ HP above 4,500 RPM.

[blykins]

I received your email and tried replying 5-6 times, but it instantly comes back to me.

My first question is are you running power brakes, or do you need manifold vacuum for anything? Second question is, where would you want the peak hp rpm to be? 5500 peak with a 6000 shift point?

To answer some of other points made here, the Air Gap is exactly the intake that I would use for this engine. It will support over 550 hp on a 418W and will pull to 6500 easily. You will find that the dual plane intakes will overlap the single plane intakes quite a bit. It's only when you get into some very large displacements (427-up) or higher rpms that they're warranted.

[blykins]

BTW, what will happen with the increased stroke is that the peak hp rpm will drop, the torque curves will get broader, and the torque will increase by quite a bit. You may not gain much more horsepower at all.

If you would be happy with a peak hp rpm of around 6000 rpm, then you could potentially reuse the camshaft you have.

[Max Power]

thanks Brent. I do have power brakes but the plan is for an eventual electric brake booster. I have a vacuum can and an electric motor connected to the brake booster.

I can live with a max rpm at or just above 6000. Given the crate engine comparisons, I was wondering if you could put me on a path similar to those. That 392 ford crate made 475 hp at 5600 rpm and max torque at 4400 rpm.

[blykins]

Here's where I am on it....

You're getting ready to add ~50 cubic inches. Your existing camshaft, even though it peaks at 6500-6600 now, will be "tamed" down by the extra displacement. My guess is that with a 408, the peak hp would be down around 6000 rpm.

To be dead honest, I would use the camshaft you have and try it. I think I could do better, but I don't know if I would make it that much better to justify a $425 purchase. A lot of my dyno testing is just A-B camshaft swaps and I've learned a ton, but there's a point where you just need to run it and see what it does.

As for more horsepower, I would look elsewhere at the car to see where you can get more power. The first place I would look would be the exhaust. Sidepipes on Cobras can be atrocious and it's not uncommon to see a 75-100 hp loss at the wheels because of it. An automatic transmission with a higher stall torque converter will also soak up horsepower on the dyno.

You're going to gain a lot of lower end power and torque with the 408. I think you'll be happy.