Hi All,

Presently working on a Miniram based 421 SBC. Just the planning stage.

Running some simulations on various camshaft options.

Heads : AFR210.

It seems like the Torque and HP performance are very similar for a range of camshaft options.

Goal : Street Motor : 1500 RPM to 6000 RPM.

224/224 @ 0.050, LSA=111, Lift = ~ 0.570", Overlap=54

236/236 @ 0.050, LSA=111, Lift = ~ 0.570", Overlap=65

236/242 @ 0.050, LSA=112, Lift = ~ 0.570", Overlap=66

Never worked with big motors. The largest to date is a 355.

Two questions for you guys.

1.
ECU Tuning.

Easy, Hard?

MAF based system. Yes, running a MAF large enough to measure the airflow.

2.
Idle characteristics?

Just looking for a decent street cam.

I ran a 218/224 @ 0.050 on a 111 LSA in my 355. It ran really well and had a decent idle sound. Nothing racy but a nice cam sound. Normal exhaust odor.

Comments?

Best Regards,

Bruce

 

I'm sorry I'm not going to be much help. I just built a 427 sbc with a HSR intake. Comp cam recommended the xr294hr on a 112lsa. They claimed it should have decent vacuum at idle and wouldn't be to hard to tune. I'll find out this spring, heh.

 

XFI292

 

Thanks Guys,

Please let us know how the 427 turns out.

I will look at the XFI292 and xr294 options.

Best Regards,

Bruce

 

Will do. I also am using AFR 220's.

 

Xfi 292 is good for that sized motor but is abit aggressive on the lobes, so would require a good valve spring. Afr 8019 springs slightly shimmed would be the ticket i think.

For more of a street car i think the old magnum high lift lobes or xe lobes would be abit softer on the valve train. For your rpm range, 242 deg duration is alittle higher than needed.

I dont think you are too far off on the 236 deg cams. I think thats about the size you want.

All those cams will tune nicely. Maf will tolerate it well. Even the 294hr

 

Thanks Orr,

How about the Compression Ratio?

10.5:1 ?

Best Regards,

Bruce

 

Thats about where you want to be for premium pump gas operation

 

Hi Orr,

Regarding the cam lobes,,,,

I looked at the Comp Lobe Catalog and found a few options. Not sure which one you are referencing?

Entreme Energy / Magnum HR Group?

or

Extreme Energy HR Group?

Best Regards,

Bruce

 

Magnum high lift group i have run on 2 different builds with good success. More aggressive stuff will make more power but also harder on valve train. Tradeoffs.

230 to 236 deg or so cam with near .600 or abit above for lift i think would be fantastic. You have a good fast port head so you dont need to keep valve open long, just lift it high and quick and it will build good cylinder pressure and make great power

 

I have a 400 stroker with AFR235s in my 89 formula
My cam is a solid roller. 260 @ .050 ish dur and right under 700 lift.
Lobe sep is 110 if i remember correctly.
I fired the car up with the new motor and drove it 8hrs on the stock tune (24lb inj) with no problems and 22mpg. It gets worse mpg the more I rip on it tho.

 

Before building the engine I would research the tuning end of things.

What intake?

 

He's using a mini ram.

 

Thanks guys,

Yes, I plan on running a Miniram. I understand that there are a few AE tuning tricks associated with this intake.

I have talked to a few folks about the tuning side. So far, the opinion is the cams that I am considering are not "big" relative to a 421 displacement. With a MAF setup (165), the tuning should not be difficult.

I am going to run a MAF that can measure the required airflow.

Please continue to send your thoughts and comments. All input is good.

Presently, I am just simulating the options.

TTOP350, I am amazed that you could run on a factory tune.

Best Regards,

Bruce

 

It may be hit or miss but like i said the stock tunes worked well on 2 combos that were between 330 and 400 whp lol. The one car would have made 350-360 whp is the valve springs were up to task for the xfi lobes. My car was a low mid 11 sec car and drove fine on stock maf tables. Wot was wayyy off but that was expected, it maxed out the sensor

 

Yeah, with the older combo I had (afr 210s and hyd roller) I was maxing the sensor at 2500-3k rpm.
With this new combo I'm prolly maxing it out sooner.
I REALLY need to have it tuned this spring.

 

Hi Guys,

Check out Blowerworks on the Web.

They have a great MAF solution for higher Flow-Rate applications. I am glad I went down this path.

I should have some Dynomation simulation results this week. Very interesting to "see" the pressure waves within the system and how the cam design modulates these guys. Will publish the data soon.

Custom cam designs can outperform (at least in simualtion) off the "off the shelf" grinds.

Best Regards,

Bruce

 

https://www.thirdgen.org/forums/alte...-421-dyno.html

Theres another example of a 421. Rather small heads but cam is about your range in size. Think it uses xe high lift lobe for .620"+ lift on intake.