Best Deal on a 408 Stroker Kit - any ideas?

[Bruceynz]

Hi Guys,

Funny how things start out and I thought this could happen, I have been offered some alloy heads, I posted here because of the big ports and the suitability on a 360 and its come in great heads for a stroker motor. I have always loved the idea of a stroker motor so I am pretty easy to persuade down that way.

So who is offering a good deal on a 360/408 stroker kit or anyone got one sitting in the garage they had big plans for and now have decided to go a different path?

Thanks
Bruce

 

[80mirada]

Hughes Engines, Scat Crankshaft (careful if you google that one some nasty things may come up) and Ohio Crankshaft have all had good prices on them. You can get Scat through Summit, Jegs and eBay. Eagle is another choice but they have had a lot of issues with quality control.

 

[Bruceynz]

Hi Guys,

So something like this

Scat 1-98111BI | Buy Scat Chrysler 360 Series 9000 Cast Pro Comp Lightweight Stroker Street-Strip Rotating Assembly at JEGS

Thanks
Bruce

 

[80mirada]

Yep, easy 400+hp. It is going to want more cam, and might need a different torque converter.

 

[Bruceynz]

It comes with this cam

Grind CRS XE275HL-10
Comp Cam 275/287
Dur @ .050 231 and 237
lift .525/.525
LSA 110

Is that cam to big for a 408 Stroker Engine? Its got some hellish lift on it! What HP would you expect out of it with speedmaster alloy heads 400Hp?

 

[80mirada]

Paired with this kit

Scat 1-98112BI | Buy Scat Chrysler 360 Series 9000 Cast Pro Comp Lightweight Stroker Street-Strip Rotating Assembly at JEGS

That cam and heads could use more compression. Plus forged pistons are like insurance . Should pull 450-475hp properly tuned. That cam can reach 450hp in a well built 360, but a 408 will build more low to mid range power and be stronger throughout.

 

[Bruceynz]

Hello,

Gas in NZ is 91 and 95 octane and there is the odd place that sell 98 but if I go out of town I don't want to be stuck for high octane gas, what comp can you safely get away with using alloy heads with the 91 or 95 octane fuel?

I have read if you run an alloy head you can get away with .75 of a point more with alloy heads, 11.3:1 is up there means it would be like having a cast head at 10.55:1 I think it is getting up there for 91/95 gas your thoughts?


Thanks
Bruce

 

[kkritsilas]

If you went with the first Scat kit, the one that Bruceynz first posted, it shows the compression at 9.4:1 with a 68 cc head. While there will be power loss and lower efficiency, it is far more usable with 91/95 octane gas than the 11.3:1 compression will be, even with aluminum heads. Mismatched some, but it should still put out close to 400 HP I would think, and should be good enough for a street driven vehicle.

 

[80mirada]

Scat 1-98113BI | Buy Scat Chrysler 360 Series 9000 Cast Pro Comp Lightweight Stroker Street-Strip Rotating Assembly at JEGS

Forged pistons will buy you some security. I got carried away on my math, 9.4:1 is enough for the cam, it would have a 2000-6000rpm power band in a 360, so it should pull stronger in a 408, 1800-5800rpm. It will make loads of power with a good dual plane (RPM/RPM Air-Gap, Stealth, Weiand 8007, or Cross-Wind). You will need adjustable rockers.

400 would be easy, properly tuned 450 is realistic

 

[Bruceynz]

Ok well over time I will get this combo together and I will be seeking advice on what I need to do to make this thing sing! I have a power limit and that is my 8.25" 3.21:1 open rear end, I think it should handle 450hp but don't really want to be shoving to much more through it. Its strong but its not an 8.75"

 

[BudW]

I think you will be good with the 8-1/4" for a while, while you are looking for something bigger.

If you are only going to drive it a couple times a month, and not on it all of the time, the 8-1/4" may last you a long time.

If you drive like I do (full throttle all of the time (he he, like is there any other way?)) and on a daily basis, then going with a 8-3/4", a 9-1/4" or a 9-3/4" (Dana 60) may be better.
A 9-1/4" will need to be cut down to fit.
A ‘66-67 8-3/4"or 9-3/4" B-body will fit without modifications to car (except for driveshaft length and/or Iso-clamp mods).
A ‘68-70 8-3/4"or 9-3/4" B-body will also fit but are slightly wider and one might need to check for wheel well clearance.


There is no replacement for displacement.
Even if you went with a mild cam 408, it will still run much better than what you have. Bigger engine will need a proportionally bigger camshaft - to get same, um, power level (not sure how to phrase this).


The big block(s), I’m building, will be mild - for I’m building them specifically for low end torque and for drivability (plus, I don’t care much for high RPM’s).
There will already be 500+ ci available (up from 400 ci) - so my opinion, why get crazy?
My engine size will 25% larger than stock, the camshaft will need to be at least 25% larger just to keep even.

 

[SirRalliart]

I really like my Hughes stroked 360 (426 cid) in my '74 Cuda. With Indy/Edelbrock heads, it made 520#-ft of torque on the Dyno. It's fun as hell on the street - it's controllable with Drag Radials, otherwise a pedal fest.

 

[High Speed Pursuit]

It comes with this cam

Grind CRS XE275HL-10
Comp Cam 275/287
Dur @ .050 231 and 237
lift .525/.525
LSA 110

Is that cam to big for a 408 Stroker Engine? Its got some hellish lift on it! What HP would you expect out of it with speedmaster alloy heads 400Hp?

Just my opinion...I think your chosen hydraulic cam will not give u what u want in a street car and more of what you don't want...my opinion is based on several issues that will most likely occur...too much lift and too much duration in a street car with your selected hydraulic cam will cause vacuum assist issues, and, that is too much lift for less than 10.25 compression ratio below 3000 rpm. Your brakes will vary from hard as a brick pedal at idle, to a very soft pedal above 3000 rpm. Once u breach 234 duration at 0.50 lift, u must (should) either get an electric vacuum pump, a vacuum canister for storage, or go to manual brakes. Imagine on a long deserted stretch of road you reach WOT and suddenly you have to stop quickly...u will have little brakes because your engine produces the least amount of vacuum at the upper ranges of rpm, and since u will be producing less than 10 in/hg of vacuum with this cam to begin with, you won't have good power braking at all. Second issue is the advertised lift being .525 int/ex....in MOPAR engines, it's always best to have higher advertised exhaust lift by a few points to allow for that last bit of exhaust gas to escape before introducing more fuel...actual lift numbers always vary. With the HL cam you have chosen, you will definitely have to replace your stock valve springs and should go to roller rockers because .525 is going to affect stock 1.6 ratio rockers and their continued alignment with the rest of the valve train... I'd say it's nearing the upper limits of stock rockers....And then there's the torque converter...u might get to stay with a 2500 stall with the HL cam, but my guess is you are looking at a 3000 stall, which will be awful with your current rear gear...overall low speed driveability will torture you. My opinion about cams in a stroker are either go with a CompCams XE274H or choose a roller cam, which produces more vacuum in the high lift area that you are seeking. With the XE274H, your normal operating range will keep u with enough vacuum from this cam for brakes, etc., and according to CompCams, you only need a 2200 stall. One last thing....your block will have to be bored, which may be a consideration for someone in NZ if something ever goes wrong because the block will be at or near its reliable bore limit.