OK, I have 406CI with 233/233 cam that dont seem to take full advantage of the AFR210 heads. I have a Holley Stealth Ram intake (see sig) that I am using. I want to stay with a HR cam and I do not want to go higher than .600 lift. AFR recommends a 242/246 cam to "really make the heads shine" Engine specs; 406-CI Bullet Billet Custom Grind HR cam 233/233, 284/289, .576 lift w/1.6rr's 11:1 CR 68 CC, AFR 210 heads hand ported and valves backcut Head flow is 297 CFM @ .600 lift Wiseco Forged Pistons, Eagle Forged Rods & 4340/Crank. 3.75 crank stroke / 5.7 rods Centerforce 400 Crank Flywheel / Centerforce DF II Clutch Flow Kooler Water pump w/ Dewitts Radiator / dual fan ZF 6 speed , Hurst Billet Shifter 3.45 rear gear Hooker 2151 cut and rewelded to clear plugs BBK 58 mm TB FMS 24 # injectors MSD 8366 Small Cap, MSD 6AL, MSD 8.5mm wires Accell Shorty Plugs 86-89,,, 165/ECM Holley Stealth Ram

Well, the main thing is, is this a daily driver, race car, or weekend car. Driving habits determines the cam size.

I think custom cam would be good for your application like camshaft innovation or whoever.

Comp has those XFI lobes and a 236/242 or 242/248 would be nice.

Looks like "enough cam" to me. Sure, you could always jam more cam in it; but for all anybody knows right now, that might just make whatever issue it has now, worse. What you've got shouldn't be grossly deficient or anything. Bullet is capable of grinding a perfectly good cam. Who over there spec'ed it for you?

What is it not doing, that you feel like it should? Got dyno #s or track times? What were the results of tuning on it? Why such small injectors? You REALLY REALLY sure it's 11:1; not just "11:1 pistons with 64cc heads" in the catalog, but you didn't zero-deck the block? Brand names and catalog specs are great, as far as they go; but alot of the details THAT MATTER, lie elsewhere, in the LABOR. What's your A/F ratio, and what kind of knock counts and BLMs and other tuning indicators are you getting?

Well Bullet/Bob suggested a 224/233 the first time and it was pitiful, they charged me to regrind it to 233/233, I had asked for a 239/244 and they said it was waaay to big.

Well, they dont know EFI for sure.

With a TPIS Miniram I only got 385RWHP / 405RWTQ, and my track times atre 12.5 @ 116mph.

SVO 24# Injectors are fine according to the BLM's.

To be specific, it is 10.97:1.
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It is a weekend car and is extremely well mannered with the 233/233.

A buddy has a 242/242 solid roller and my 233/233 was patterend after his TPIS cam but in a Hyd-Roller version by Bullet.

Bob is probably the best there is. You would agree if you saw his resume.

You can't tell anything about WOT from BLMs. All that those will tell you, si that yo've got your pulse width set up about right at cruise; they're telling you that the ECM doesn't have to do too much trimming based on feedback from the O2 sensor. None of that is active at WOT.

Fact of the matter, HP comes from fuel, and 24 lbs/hr is only good for just so much HP. The exact amount depends on the engine's BSFC. I can DEFINITELY tell you though, 24 lbs/hr is generally just barely enough for a 350 with alot less intake than you have now (HSR setups). Stock LS1 (346 CID) injectors are 26 lbs/hr.

I ran the numbers not too long ago for a 434 MiniRam, with slightly more cam than you've got (242°/248° solid roller); came up with around 38-40 lbs/hr injector requirements.

Just TRY some 30 #ers and see what happens. It'll need some chip work to run right anywhere but WOT, with that big of a change; but see what happens at WOT. As easy as it is to change injectors with the MR, that'd be the first thing to try.

I don't trust "10.97:1" any more than I trusted 11:1. What's your measured deck clearance? Exact measured head cc's?

I believe it would be mild-mannered. I drove around a 400 with a 230°/236° hyd roller in it for years as my daily driver. Made 2 coast-to-coast trips with it. But, just being "mild-mannered" doesn't necessarily keep it from being able to lay down some serious numbers.

OK, I think I have all I need now, thanks sofa king!

so it sounds like you want more power from this combo right, A hydraulic roller would have to be bigger than the solid to make the same power. You need a bigger cam to optimize those heads.

If you want to estimate your injector needs, use:

Your engine's BSFC x HP ÷ # of cyls ÷ max duty cycle = the injectors you need

BSFC is "brake specific fuel consumption". It's in units of lbs/hr/HP. It means, the amount of fuel that your particular engine takes to produce each HP, per hour. (i.e. run the engine for 1 hour at x HP, it used y pounds of fuel, BSFC is therefore y/x) Typical BSFCs for good running streetable cars are somewhere around .45 to .48. That's assuming optimal tune, generally efficient operation, etc. Lower numbers correspond to getting more HP out of the fuel; professional race cars get BSFCs well down into the 30s sometimes. So, use .48 in an example we'll create here, just to put it into perspective.

If you're putting 385 HP to the wheels, then that's about 475 at the crank. Let's plug 475 into the equation.

8 cyls (duh)

Max duty cycle usually should be kept to about 85%. Any more than that, and you're mighty close to the injectors going "static". The OEMs are often more conservative, and keep theirs to 80%, but we'll go for broke here. So let's plug .85 into the equation.

.48 x 475 ÷ 8 ÷ .85 = 33.5 lbs/hr is your fuel requirement

And there's your problem. Now of course you can get somewhat more fuel than the injector rating by bumping the FP; but that only works just so far, and then beyond that causes its own set of problems.

Look at the reading off of the wideband from your dyno run. I'd be willing to bet that your A/F went close to, if not above, 15:1 at peak HP.

Which means, you're probably 10-15% down on HP from where you COULD be, with nothing but a better injector size.

I agree 100% with Sofakingdom. 24's just cannot get enough fuel at that power at probably 6500 RPM redline. Plus your MAF is probably maxed out at like 3500 RPM at WOT, and is going blind from there. Buy, borrow, or steal a wideband, and see for yourself how good it is.

I can't seem to find your post on the corvette site - mind updating that link?

Well, the engine will be pulled in a week or two, then I will set it all back up with a new McLeod Twin Disk, and take it back to the dyno.

I will post a dyno run by mid June, barring any more unexpected problems.

Link Fixed

Not to hijack, but, i was wondering what kind of computer tuning, if any, is needed for running the HSR? Thanks

Stock 1986-1989 ECM with a custom tune, but I have a 406CI too

I've always heard that it likes a lot of timing. I'm running 22* at idle to keep it from surging so much on my 383.

I will clarify further, 6* by the dizzy + 16* in the SA table in the computer = 22* total at idle.

Wow - 22* at idle??!? Is that common???

233/233 is a good cam for a street strip 383... definately go abit bigger on the cam but i agree on the injectors... i'd use 30's or 36's

385 does seem a tad low for that combo. i'd expect abit over 400whp easy.

Most run about 17-20 at idle. Mine seems happy at 22. I'm going to work on it a little more to see if I can get it done to about 20.

Interesting. I've been familiar with the standard 6-10 deg. used on more "stock-type" vehicles, & I just figured that I'd use that as a starting point w/ the new intake... Thanks, you might've saved me a bit of grief!

Those "stock" numbers are for EST Bypass mode to set the timing for computer controlled cars (set by disconnecting the EST Bypass wire (Tan/Black), reconnect after timing is set). This is commonly referred to as Base Timing. That timing is used only during cranking. After that, the computer takes over and advances the timing.

Big cams need more timing to behave at idle. 22 is not a lot actually. They can also require a little more base timing to help cranking (but that must match the chip's base timing setting).

Well, I decided to keep my cam, then go to the dyno, then I will consider moving from 3.45's to 3.73's or similar.

My injectors are fine so when I get my dyno #'s I will post the results, probably mid June

Just because your blm's are in line does not mean your ok....
But you'll find that out on the dyno.

All of us are telling you that your injactors are NOT fine,
noone agrees with you and you still dont belive...
Now, how can we call that behavior..?

"all of us" ,, I dont see any helpful info or insight from you regarding this post,,,,


Thanks for your help,, NOT

i dont know man, i think u could use more fuel....your overworking those 24lb injectors

Injectors are a huge debate, always, I agree that you don't want the injectors to go static but at prolonged WOT they can.

During normal spirited driving they do not go static and do not hit the 85% mark.


No offense, but , This thread was started because I wanted to know if I could get more out of the AFR210 heads, which I believe I can, but not so much with a Hyd-Roller.

Someone else made the comment about the injectors being too small and others jumped on the band wagon.

I will not post any more replys on this thread until I have been to the dyno when the engine is back in, so Mid June, early July, I'll post my dyno runs,

in the mean time I have cut my old shock towers off and I am wedling on new thicker CRS towers to accommodate my new QA1 Coil over setup,

then I have to put my new SCAT crank, Flywheel in after my machine shop balances it to my bob-weights, and I am also replcicng my PUSH type clutch that will replace the ZF Pull type POS clutch, then I will burn some chips and go to the Dyno.

Sayonara! See you in a few!
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Also, here isa link to CORKVETTE1 in PA, running 127.7MPH at 10./27 using a 24 # injectors and 85VET running 10.8 with 24#'s.

http://forums.corvetteforum.com/show...ight=corkvette

You need more injector. I'm running a 350/MiniRam/ZZ409 cam/Worked 113Dports and I have my FP set to 50psi and the logs show about 85-88% duty cycle at WOT under load. I'm about 425 Fhp. You are leaving a lot on the table.

if you want more power out of the heads, you need to add more fuel. your askin if there is more room in the heads to allow more flow, well there is...but it doesnt do good if the fuel isnt there to make use of that extra flow.

but i do agree that 210's seem to flow alot of air especially at higher lifts like over 600. i think u'd like a solid roller or more duration on that hydro roller cam. definately have more room for a bigger cam with those heads

You must not have ever looked at a .bin before. Even stock 305 TPI's run more than 22 deg idle-most in the 24-25 range, stock from the factory. It sounds like a lot if you are used to setting a carbed dist. a 10 BTDC -- but remember, when you are setting a carbed dist. you have the vac advance disconnected -- once you plug it back in, you will have similar numbers just off idle anyway.