newbvetteguy

The comment that a FIRST Fuel Injection intake is the wrong choice for most street builds is pretty nonsensical.

Many folks with street-focused GEN1 SBCs are afraid to spin beyond 5,500 RPM; if your goal is the max power up to 6,000 RPM, that's pretty much exactly what you'll get with the FIRST. It's ideal application IS a typical street 350 / 383 SBC.


You'll get more torque and more VE; more air stuffed into the cylinders picking up the 2nd wave than the 3rd wave.


My torque peak with a pretty aggressive street hydraulic roller at a first should be at 4,500 and Mike Jones says HP peak @ 5,800 and not falling off until 6,200-6,300; BadSS modeled my combo in EA Pro and came with basically identical results.

I took my 1979 350 bottom-end and am bolting a $998 set of Jegs Profiler 195cc heads, an untouched (gasket match) FIRST $1,050, and installing a hydraulic roller cam and I should have 440hp and more ft lbs than that @ 4,500. My fuel economy will definitely double my current 11 mpg (nothing done to the block except a 0.015" thin felpro gasket to get to 10.2:1 static CR).


This is a super common street build and the FIRST is perfect for it. A short runner intake is not going to touch the First intake's power within the 1,000 RPM surrounding my torque peak (4,000-,5000 RPM)- maybe from 5,000 RPM to my hp peak of around 5,850 a shorter runner intake would do better than the FIRST, but on the top-end it's still only picking up the 3rd wave and it's going to give up WAY more HP and torque in the middle of the curve.


If I'm not going to spin beyond 6,000 RPM, the shorter runner gives me power where I can't use it and requires going with a bigger and/or shorter header that gives up still more street torque and power down low and at highway cruise RPM (mpg); then a bigger stall TC for more lost mpg and less streetability.


Here's a 383 Crate Motor running a FIRST Fuel Injection intake and making 460hp and 520 ft lbs of torque, with the Tremec's T56's super low 6th gear it probably can cruise around at 24mpg; this intake is IMHO not just a GOOD choice for a street build, it's almost ideal. As has been proven you can run high 11s in a good 350 with this intake. http://rcsracingengines.com/Perf%20C...evy%20EFI.html


Seriously what more do you want out of the thing?

Giving up the low and midrange grunt to gain HP between 5,000 & 6,000 RPM to get a slightly higher max HP # would be really dumb; it's a bad trade-off.



The examples of other TPI-style intakes aren't particularly relevant, either as their flow #s aren't in the same ballpark as the FIRST; the FIRST has a slightly shorter plenum-to-valve runner length of 19.25", but the added diameter also slightly moves the wave tuning up in RPM, as I'm sure you probably know already. Moving the torque and HP peaks further upward a couple hundred RPM with the siamesed runner option only makes it that much better for the bigger cubic inch builds or 350s @ 6,500 RPM builds. (BadSS- can you run the intake tuning sim in EA Pro with both the siamesing AND increased diameter in there to see what the natural tuned RPM would be? Then a combo with a nice, aggressive lobed 235 @ 0.050" duration cam in a 383?)





Adam

Orr89RocZ

iTrader: (20)

You are acting like 23 deg heads cant rpm or cant flow. Theres 850+ hp race naturally aspirated 23 deg sbc heads out there. Shallower Valve angle is NOT needed on a street car

No factory ls head is gonna make that power. Closest would be a ls7 head in a na race form. Even the venerable trick flow 245 heads will have a hard time doing 800 all motor


Valve angle wont overcome a long run length either unless that runner is of large enough diamter not to be a restriction in flow to support the head. Theres a tuned length for a rpm for a given cubes. Regardless of valve angle. Engine only sees air flow, it dont care how it gets it. If you build the setup around the parts you need for the goals, you'll find it doesnt matter if its shallow angle lsx head or a sbc.

For budget concerns the ls factory head stuff cant be beat. They do win there

firstperf1

I am trying boss!

Ken

newbvetteguy

I think you've put a few words in my mouth; could be that I'm miscommunicating.

I didn't say that 23 degree heads can't flow; I said that the lower degree stuff will flow more and with more velocity for the same CSA.

I also didn't mention factory heads, although for the money factory LS heads with their lower valve angles do flow more than factory 23 degree stuff obviously.


I didn't say that you could attach a long runner intake to a low valve angle head and magically overcome how tuning works and spinout more RPMs; but you could make more hp with the same duration cam and same max RPM with a lower valve angle head (you can make more HP at a streetable RPM range with the extra flow and you'd end up with great torque as the reduced valve angle heads can flow more air at the same CSA).



Lower valve angle 23 degree stuff would be nice.


See the Profiler 13 degree heads for an example: 370 CFM of flow at 0.600" of lift, and $1,130. A 13 degree head could be made with a 64 cc chamber and stud-based rockers and a similar CSA to the 23 degree 195cc Profilers and would flow way more (more flow with same CSA also means more port speed and torque. -They would make more power than a 23 degree head and with stud-based rockers and could be affordable with a matched, cast intake and off-the-shelf header (that doesn't exist today, obviously).

Lower degree SBC heads at this price point would be a great response to the LS heads, IMHO. Gain 40+ CFM on 23 degree AFR head for considerably less $$ would be a no brainer; all existing LS engines show the benefit and don't have "streetability" problems.

It's the only tech that hasn't "trickled down" to the SBC street space; obviously, it's everywhere with the LS motors.



Adam

Orr89RocZ

iTrader: (20)

The market is not there for small port low degree sbc heads. The 23 deg stuff already does more than most need. Granted it would be nice to see, but it just isn't economical

anesthes

iTrader: (12)

It's cuz a lot of hot rod guys don't mind crappy idles, and having to wind the crap out of it to make it work.

Do you remember when Comp came out with the tumpr cams? People actually wanted a cam to make their aggressive!

You are spot on, guys buying 23* stuff are racing or don't care how bad it runs. Guys that want smooth purrrrfection and power are buying LS stuff. Or brand new Corvettes, which it seems like everyone and their grandmother has now.


-- Joe

Orr89RocZ

iTrader: (20)

I disagree. Its tuning. Good efi will make anything work fine. I know many ls setups with "stage 3 or 4" cams that drive no different than a big cam sbc.

I dont understand why people are having issues

Guys build ls cuz they are cheaper to yank out of the jy and cam for 400-450 hp than to properly build a sbc. Gm already did the heavy lifting. Its fool proof and i dont blame guys for doing it.
But thats NOT to say ls is superior by any means in design. Sbc can certainly compete in power production and still drive well. Just dont expect it to be that cheap to do right.

I will say this however, on average the lsx does seem more efficient on fuel economy, but again some of that is in the tuneup

newbvetteguy

Is it a chicken problem, or an egg problem, though? / A supply or a demand problem? (there's no supply currently so hard to say definitively)


It's easy to say that there's no market, because there's no product.


Again, you've got Profiler selling a 12 degree SBC head with 370-380 CFM of flow for $1,100 today; but very much race-focused with tiny chambers and shaft rocker support only.

AFR 210cc are$1,825; $2,165 for the Comp Race version they flow 301-311 CFM

AFR 195cc are $1,700; $2,135 for the Comp Race version; they flow 275-280 CFM; 308 CFM for the comp race version



It's not casting a set of 12 degree heads that costs more (as can be seen by the cost of the bare Profiler 12 deg heads ; it's the valve train components, which is why a stud-mounted valve train setup would help bring the prices way closer .


If you could buy an AFR Comp 64cc 195cc for $1,700 with a min CSA of 2.19" and 280 CFM, but also had the option to buy a Profiler 12 Degree, 64cc head with the same 2.19" min CSA and 320 CFM (40 CFM more), for the same $1,700, you wouldn't do it? Yes, the advertised port size in the 12 degree head would be bigger because the port is longer, but the CSA to CSA comparison is "apples to apples"


-The 12 degree head would have more average torque and average HP than the 23 degree head with whichever RPM range and cam you choose; more power everywhere.





It's not that low valve angle SBC street heads have been tried and been found lacking; it's that they haven't been tried.

Adam

Orr89RocZ

iTrader: (20)

No because flow doesnt mean anything. A street motor making 500 hp is only gonna use 250-275 cfm. Why do you want to buy one that flows 320? The best combination is where all the components match. Its not solely about flow numbers

Nothing to do with chickens or eggs. The factory made 23 deg. Aftermarket companies followed copies and improved designs. Power is being made to satisfy the masses

95% of street na builds will fall between 300-650 hp for a sbc or ls for that matter. Most sbc or ls are 350-434 cubes. If you never been around a true honest 550-650 na hp sbc or ls for that matter, you would know thats a ton of power for a na motor and most will never operate at higher levels because then you will need much more rpm and cam, which takes away from drivability. This power is 3500-7000. Some more tolerant individuals go higher rpm. But it certainly starts taking away drivability and longevity and cost alot more either way. My friends 416" ls3 stroker makes 620 hp na at motor. 530 whp. Runs 10's at 3550 lbs street car. Very aggressive engine. Other friend had a 406 sbc, afr 210. Also 520 whp runs 10's 3400 lbs. also aggressive. Both make same power yet two different approaches.

To make much more than 600 on pump fuels is a very well developed engine. Sure low valve angle heads may help this some but the market is small. You want more power? Go forced induction or nitrous as you see with junkyard stock lsx motors now.

Gm did low angle heads to be more efficient at making power WITH emissions. Needed a head that could produce flow, efficient burn for emissions and mileage while doing it with a small cam lobe. This combo makes for a great driving efficient setup that will last 200k miles. Hot rodders dont concern themselves with this. Very few do.

newbvetteguy

Orr,

Much of my thinking on why the low valve angle heads would be better on a streetable SBC comes from your posts on SpeedTalk; i'm having difficulty squaring what you said there on the subject vs. in this thread. Have your opinions changed, or what am I missing?


"What about head flow at smaller and larger depressions than the standard 28"? IF they all flow 300 cfm at 28", how do they look at say 36"? Motors will see higher depressions so with the valve angle change more inline with the port, I would think the lower angle heads would have higher flow potential, given similar valve sizes and valve seat angles.

A stock LS6 head being 15 deg adn 211cc flows in the 260cfm range depending on what bench you used. My AFR sbc 195cc heads flow 280cfm. I put them on a 383 with a 230 deg, .603" lift cam and made 400whp. 346 cube LS6's with similar 230 deg .600+ lift cams are making closer to 430-440whp. Similar RPM band, with the LS peaking slightly higher and their heads flow 20-25cfm less!

Thats the reason I think the LS 15 deg heads make more power even tho the "flowbench" says it wont due to flow.

Most sbc 18 deg 15 deg type setups are targeted to big cubic inch or high rpm motor combinations and have a big port and big valves. LS stuff is more for street setups, somewhat big valves depending on the heads, but smaller ports. The cathedral port stuff has 2.00-2.050 valves depending on the port work. SO they are generally smaller valved for the smaller sub 4" bores. The larger bore LS motors can use the rectangular port heads which are huge ports but small CSA and huge valves. The small CSA and higher velocity makes some torque so you can still use them on a street 364-370" motor.

I dont think you could put a typical 18deg sbc head on a 355-383 and expect it to be as driveable with a baby cam as the LS heads...so the port shape is a big factor.

So it would be tough to say what would happen if a 18deg sbc vs 15 deg LS vs 23 deg sbc faced off. Even if they flowed the same, I'd have my money on the LS head for more average power with mild cams. If you did a full race setup and could use the 18 deg sbc head's port CSA size to its advantage by turning some rpm, I'd think that would win in a power shootout. But there are some SERIOUS 23 deg sbc heads out there and some SERIOUS LSx heads out there that all can make 700+Hp."


Your comparison of an LS6 head @ 15 degrees and 260 CFM making 40 HP more than a better flowing 23 Deg AFR 195cc head flowing 280 CFM, is to me a prime example of why the SBC platform could really benefit from the lower valve angle heads.

If you can get more HP per CFM out of the lower valve angle heads AND even 15-20 CFM more for the same CSA with a 12 deg head than a 23 degree head, then you make more HP and more torque even with baby street cams. --Instead of 40 HP more with a 230 degree cam, if you have the same flow maybe you're at 60hp or 80 HP more. The crappy SBC exhaust ports should get better with the lower valve angles, too; no?


40-80 HP for a little more money in a very streetable combo seems like a great return on investment.


How many people jumped to AFR after they came out and went on a marketing blitz and proved they were even a few CFM, HP, and FT Lbs better than the alternatives for the money?

There's something about being the "Best" for similar money that seems to result in an instant market; I think there's always a market in this hobby for a new "best" especially if we're talking about best by 40 or more HP for any given cam duration...



Adam

newbvetteguy

I think I kind have to agree with where Anesthes is going, which is that GM's now got two very different markets and significant product differentiation and Brands between the old SBC platform and the LS market.

You've got the lumpy, sounding, crappy idle Hot Rod- GO FAST and to hell with fuel economy SBC market and the "daily-driver Go-Fast modern performance market in the LS motors".


A lot of companies work hard for that kind of product differentiation and clarity of marketing; they might be dumb to muddy the waters with LS-like SBCs and like you said many of the things the low valve angles bring (other than the fairly significant performance improvements) may not be highly valued in the SBC market.



I probably just want it because I know I can't have it; lol!


Adam

Orr89RocZ

iTrader: (20)

All of what i said in the past still applies. I said flow doesnt seem to matter on a bench as you can see by some examples like the ls6 head. Its important in a sense but there is alot more to it.

Simply stating a small port 15-18 deg sbc head would be better because it may flow more is not necessarily the case but theory would suggest it would.

23 deg heads are velocity limited. They have to get big to flow well and support larger cubes and rpm. Lower angle can handle more velocity in port. The better the head the smaller the cam can be for a given power. The ls is more effective in making a given power with smaller cams than most 23 deg sbc stuff

But as i tried to elude to earlier, your typical street na power level and power band can be covered well enough with the available 23 deg design. They have come along way with all the shops offering port work or their own cnc heads. Because of this the market does not see demand for a small port 15-18 deg design. You'd have to make new cast heads, pistons for those heads, rockers for the heads, possibly lifters with offset depending where everything ends up geometry wise. Then you need new intake manifolds for them. Alot of extra stuff, the whole market would need to produce items. I just dont see the need for it in the basic street car. If you want ultimate small cam drivability get an ls efi car. But every good efi sbc i have done or been around has been fine

newbvetteguy

Ok, now I think I'm starting to understand.

Why on earth would you need new pistons?

Why would you need off-set lifters? (if you move the position of the valves too much the rods would hit the lifter bores when the lifters move into their lowest position or something? -Even with how high the pushrods set on retrofit roller lifters?


I get the different intakes and different headers thing; but I don't understand the need for different pistons or offset lifters nor what offset lifters would exactly mean.


Adam

Orr89RocZ

iTrader: (20)

Valve angle changes, the chamber shape changes so valve drop changes. This means may need alot more valve relief cut into the piston. Also depends how they do it. If they space the valves differently like a 60/40 spacing it may need a wider or different position relief

If you run a dome for race guys that want to run them, they need different design.

Then again might not. Most 12-18 deg heads have huge valves requiring different valve spacing and such. If a small valve 15-18 deg head then might not need it.

Pushrod angle may be affected depending on shape of the head. Where they position the rockers and such, may require offset rockers or lifters. Lot of big port 23 and 15-18 deg stuff requires it. Suppose a port could be made to not need special parts since it will be smaller. Idk

Street Lethal

iTrader: (16)

That's not necessarily the case. Back in the day, the choices for upgrading valve-train components were limited, and most guys were not looking to spend a lot of money. It didn't take rocket science for them to figure out that duration was the key to making big power at lower RPM's, thus the term "torque motors" because hardly any of them revved past 5000-RPM on the street, and by revved past 5000-RPM I mean they didn't make any power beyond that point so it would have been pointless. Yes the small blocks revved, but at a cost because they kept breaking, so guys were more into cubic inch displacement because they lasted longer while making more torque. Replacement valves and pushrods, hell even lifters were a junkyard away. Keeping cost down, power up, but at the cost of increased overlap. Vizard profited from this lack of knowledge off of the average enthusiast, but cam companies soon woke up and starting seeing the benefit of different lobes and ramp rates. But again, it came with a price in which most enthusiasts continued to avoid investing in. This is why the SBC has the reputation that it does. If AFR made their cylinder heads at a much more reasonable price to be used in conjunction with a more custom roller camshaft also reasonably priced, you would have seen a tremendous difference out on the street back then. You rarely, if ever, seen a SBC fitted with the best of things being offered by the aftermarket, even today most guys want a bargain. Nobody had the money, not to mention it took away from the "DIY" aspect of hot rodding when guys can simply port their own parts. I mean think about it, if the year was 1988, and GM released the Iroc-Z with a Holley Stealth Ram, custom roller camshaft, AFR heads, larger injectors, more aggressive tune, along with a higher stall speed, it would have been the fastest thing on the street back then. Period. It just didn't work out that way, and GM was already way ahead developing engines like the LT1 and LT5, soon followed by the LS during that time. As for "Go Fast" modern day performance, I would take a 25 year old LT5 over any LSX any day of the week...

- Rob

BadSS

FYI - TrickFlow hit the market with a 13-degree low valve angle head to take a stock intake over 30-years ago with their 180cc Twisted Wedge Head. I liked them for what they were, owned and ran a set, but with them being very limited in their use and a bad batch of springs on the original run pretty much doomed them to obscurity.

Here’s a couple links with some info on them:
An old 1997 article
http://www.hotrod.com/articles/trick...ead-dyno-test/

and the instruction sheet on the heads. They flowed just a little better than the typical Vortec head out of the box. There were some reports of ported sets flowing more than 320cfm but the juice wasn't worth the squeeze.
http://hbassociates.us/Twisted_Wedge...structions.pdf

It’s kinda like everything else, one “improvement” in and by itself usually doesn’t do much and usually falls within the gimmick range of things.

I understand what you're saying but if the old SBC stuff won't fit your needs, then go LS. The swap kits are there for just about everything. I went with the old SBC because I already had a good set of 23-degree heads and wanted to run this FIRST since the late 80s. If I had been starting from scratch, I'd be running a big cube LS.