I am about to order the TFS heads for the 305s in a few hours and I am curious as to what and where my hp/tq should be. Is there anyone that could help me with a desktop dyno program? Even some educated guesses are welcome.

My setup
HSR intake, 21lb injectors idk if that matters, TFS 305 heads, zz4 cam, 1.5rr, hooker 1 5/8 primaries 3" collector, 3" exhaust, no cats, spiral flow muffler, no smog, no ac, maf screens deleted, cai

any help would be appreciated

 

The problem with desktop dyno is that it usually over estimates. At least I've seen that true with my version, which is 2k3. If I had a guess I'd say 250-260hp (@ the crank) around 5000-5500, and 280-300ftlb torque (@ the crank) around 3000-3500. Anyone second?

 

o i can guarantee it will be more than 260hp at the crank lol. My guess was about 320.. there was an engine build that used heads that flowed a little less but they used a larger cam and spun the engine up pretty high and ended up making 373hp i think. but that was with dyno headers and no exhaust

 

Here's what I came up with in DD2003 using that setup.

Keep in mind DD predicts with perfect tune and atmosphere. And of course it isn't dead accurate that should go with out saying. It's not a magical digital dyno, it's a estimating calculator.

I've had different results with DD then Douchermann, sometimes it's over estimating, sometimes under, others it's scary close. I got bored one night and compared a good amount of Atilla's builds he listed to DD and got some very close end results. There is a lot of variables involved, the inputted data accuracy, tune and atmosphere of "real" motor, among other things.

Some things you need to think about though. The heads can flow all they want but if the intake flows less so does the heads. This shouldn't be a problem with the HSR just throwing the information out there. DD2003 doesn't have a HSR option for TPI though so you may see better peak HP if your tune is on.

Also do not pick your injectors BEFORE the build. They are picked based on what the motor needs not what you want it to have.

 

those are just the injectors i have now but i am pretty sure they should be sufficient, if not, ill get bigger... I know the DD is just an estimate but thats what i want. A lot of estimates and if i ever find a dyno in my area ill have a run and see what it really makes.
So what did you have to do for the tpi cfm then? since there isnt an hsr option? could a certain carb intake be substituted instead? the one the hsr was designed after?

 

What was the HSR designed after? I was using 550CFM with TPI injection. Using 750CFM and TPI the peak HP is 337 @ 5500 and TRQ 354 @ 4000. If you use a carb and high flow dual plane its a different animal peaking at 378hp @ 6000.

Sorry for all the "qualifying" of the DD results, you gotta get all that out of the way because people get all emotional when you start using DD for some reason.

 

supposed to highly resemble the tunnel ram i beleive

 

Should use a bit more cam than that. Compliments the HSR and heads more.
Didnt run DD, but i'd guess close to 300-310 on motor wouldnt be out of the question.

Probably 250whp?

 

The ZZ4 cam uses I.R. lobes, so you really should respect GM's suggested redline of 5800 with that cam. That being the case, get some 1.6:1 rockers for the intake, which would change the DD input to 210/221, 506/510, 112 at 110 ( spec is 109, but most timing chains stretch )
Input a tunnel ram intake manifold, too.

 

how many CFM is the intake?

 

i know its 275cfm per runner, im not sure on entire intake..

which cam would you recommend? its just a resurfaced stock crank and reconditioned rods with arp bolts

 

I don't believe that. Maybe the carbureted version can do 275, but I've seen a cut-open HSR plenum. Just go with whatever the heads are, and that'll still be optimistic.
Since the HSR can be made to accept a twin-58 mm TB, there's no issue there.
What's wrong with the ZZ4 cam? Especially since you're just a 305. But if you insist on losing below 3000 to gain above 5000, then go with the HOT.

 

this is what i found.. Runners (measured individually)
HOLLEY STEALTH RAM Stock....................275 cfm
HOLLEY STEALTH RAM ported..................298 cfm

the link i found it is here http://forums.hybridz.org/index.php?showtopic=20281

the heads are 242@.5 and 242@.6 intake, 172@.5 and 180@.6 ex

 

The runners aren't the problem. The problem is trying to get the air to make the 90-degree turn from the plenum into the runners. There's just no radius there, no dams, nothing to make it happen. It doesn't matter how much air the runners can deliver, it's how much air can make that 90-degree turn. And it's nowhere near 275.

 

as far as the cam im not concerned about trade off for driveability. I just cant rev past 6k with the basicaly stock bottom end so idk what would be better. btw, ive never heard of I.R. lobes?

do you think the throttle body would hold me back? i have a bored tb to 52mm but havnt used it. should i? I see a lot of criticism when people slap on bigger throttle bodies.

 

Consider that the RamJet 502 crate engine uses the exact same throttle body as the '91 Corvette TPI 350. If that twin-48 mm TB can support 500 HP, why go bigger? There are many airfoils on the market for your TB, and those are worth buying.
I.R. lobes are Inverted Radius.
I can tell you from my 2 years spent with a used, 120,000 mile '91 LO3, that making the 1-2 shift at 6200 rpm, time after time, is not a problem for the stock bottom end. Just need more airflow than the LO3 cam, heads and manifolds can provide.
I did it light after light, day after day, week after month. If it was gonna cause the failure I was hoping for, it would've failed for me.
By that reasoning, and based on what you typed, go ahead and try the HOT cam.

 

I dont know how much the plenum effects the air flow in the manifold. It has a big plenum with good volume so the motor should beable to feed without too much issue. HSR has been used on many very high hp builds, so its definately capable of delivering flow. More than enough for a 305. Keep the 48mm tb.

ZZ4 cams typically go to 5500 and start to fall off in a 350 motor. Its enough to make 345-350hp on a 113 headed 350. On a 305, I bet it can get up near 5800 or so before starting to die. Not a bad choice for a 305 I guess. Considering 45 inches less cubes, expect to see 40 less hp or so?. 300-310hp on motor wouldnt be a bad estimate in my opinion.

 

These TFS 175 heads flow much better then 113 L98's.

This is where it gets tricky doing estimates with DD I guess. Using 270cfm for the induction doesn't seem right. When we rate carbs, say 700cfm, that 700cfm is split between the 4 cylinders as they fire. I'm not sure how DD interprets the tunnel ram's CFM; being per cylinder or overall, like a carb.

Now if it's "smart enough" to know that it's getting rated per runner I have results for what you want and what Atilla suggested. I say all this because I'm seeing huge differences between 270cfm and say 600cfm.

 

Orr89RocZ, your reasoning is sound, but my experience is that any given 350 build transferred to a comparable 305 tends to make the same power at higher rpm. Thus a ZZ305 should still be 340+ hp, but instead of peaking at 5250, would likely peak at 5600.
Doom, please show the results of 600 cfm, and the results of 242 cfm, provided both are between 310 HP and 355 HP. If either one isn't, then it's not realistic enough to look at.

 

That was my concern Atilla was throwing out some crazy numbers because it is showing 50+hp increase switching to 600cfm. With 600cfm selected its showing 406hp @ 6000, which is more then using a high flow single plane and 750cfm carb, so I don't trust it.

I did some research for a good hour looking for solid flow numbers from the fully assembled unit but can't find anything solid. A lot of, the TB flows this, the runners flow that, and the base. But not together.

Anyway attached is a screen shot of your setup using 275cfm flow and a tunnel ram for induction.

The solid line is setup as Atilla suggested with 1.6rr on the intakes and you can see it makes more power at every RPM, the ratio is even better after peak.

 

im going to blow up my t5

 

Not if you don't drive abusively. The 1.6 intake rockers would be worth more than that, because the program can't account for the reduction in friction that comes from switching to full-roller rockers.

 

i have full roller 1.5 now but ill look into some 1.6 for the intake

do you think these heads will change the sound of the cam and or exhaust much?

 

Sounds good. I was just guessing based on the smaller bore size that overall flow thru the valve would be decreased enough to show a hp loss compared to the 350. I've seen some guys 355 motors make the same hp as a 383 with same heads/cam, but the 383 made it at lower rpm and made more torque.
I would like to see some decent 305 builds, as you never really hear about it. If they have decent potential you can make them into a pretty fun street car.

 

I've seen good, mild 351W combos done to 302s, and the HP tends to increase. So the 305 shrouding could explain why it seems to stay about the same.

 

You're right on. It's only counting lift.

I'm going to be honest and say I think these heads are fully capable of +400hp @ 6000ish RPM on a built 305. Roller block, 10.5cr, long tubes, ect.

This build will love compression with that cam and these heads. If you can raise compression while still having proper quench it will be well worth it.

 

First, if the stupid program has an input for rocker ratio, tell it 1.5:1 intake, then tell it the cam is 210 intake duration, and that'll be more accurate. Because that's the effect that 1.6 rockers have in a SBC, but most people discount it. Losers.
Second, with SpeedPro H534CP60s 0.023" in the hole, FelPro 1094s, and the TFS heads at 56cc, that's 10.42:1.
That will be safe with the HOT cam, and you should top 400 horses at the crankshaft, assuming no accessories but the alternator. I suggest NOT using any 1.6:1 rockers if you use the HOT cam. They won't gain anything down low, and they'll hurt it from 5600 on up through 6200. With 1.5s, the HOT is 218/228-112@110 (timing chain stretch) and 492/492.

 

the pistons are .030 speed pro

 

Send them back and get 60s.

 

still equals 10.24 or somewhere close with .025" i think..

 

just for reference.. i put the 52mm on out of boredom and im glad i did. drivability improved and strangely it really opened up after 5.5k.. i mean reallllly opened up