If you wanna stretch the heads you need to dump the tpi

 

True that. I tend to think of these things in terms of what I have. Not to mention what my targets might be.
When GD wrote:

To me it's leave well enough alone. Stepping up would not only mean ditching the TPI as suggested, but the stock bottom end wouldn't be long for this world (my world anyway) if you want to tap into the full potential of those heads.

 

With just the heads I think anything lost will be pretty much unnoticeable. Its going to be such a small loss that part throttle at slow engine speeds (like highway in OD) that if it gets enough throttle that the converter unlocks it will stall and hide any loss. And once the foot goes down to the floor the downshift will put it in a part of the power band where its making more power already.

I don't know moving to a higher duration cam is going to help much. The First flows real nice, but it's still a LTR setup. Trying to make power beyond 6000rpm is going come with a cost down low.

However, there is the fact that the AFR heads exhaust is MUCH better, so a split pattern cam isn't really required. Could move to a single pattern cam with with more duration on the intake and still maintain a similar level of overlap. Combined with more lift would provide more power while keeping similar idle qualities.

My cam's split is 231/239, and I've been considering moving to a single pattern cam, with a wider LSA.

 

I dont think it will lose anything on the bottom end at all

 

Probably not down to where the dyno would pull it anyway.

 

Looking at other Dyno results online, it seems the AFR heads track very similarly to a Vortec on the low end, but then diverge dramatically up top. The cam test article I read showed 40-50 HP gain with every cam on the AFR over the iron Vortec, with a shift of peak HP of about 400 RPM.

If I gain 40 crank HP that is almost certainly going to put me over 350 at the rear wheels. Won't take much spray to get to 500 or a low amount of boost with E85.

And yeah - pretty much anything below 3000-3500 RPM is unreadable for me with my converter. Not that it doesn't matter at all, but it doesn't matter much and not having a significant change down there isn't going to be noticeable.

GD

 

Thats my thoughts too. If you are happy with the torque down low right now, then the AFR heads are just going to give you everything you have now, but dramatically more as RPM increases, right up until you get to the limits of airflow allowed by the valve events.

 

I'm thinking more along the lines when you're in OD with converter locked up and lugging it down the highway. 2000 RPM maybe. Me, I'm at 2350 @ 70 mph (3.73 gear, 26" tire).
Interestingly, I'm finding very little (or credible) published flow data for any AFR heads at .100". And nothing just off the seat at .050". Which is where the Vortec earn their reputation.
By the way, which AFRs are you getting?
Anyway, it'll be interesting to see the results.
If my current heads are smoked (to be determined this winter) then I'll likely follow the same path as GD. Or similar. I've always liked what Chad Speier does to set of average cylinder heads....

 

He got the current gen eliminator 195cc heads with the upgraded valve-train.

Same heads I have on my car, but I have a much bigger cam and a heavily ported LT1 intake. They'll feed a 350 to 7500rpm all day long.

 

The Street Eliminator I assume rather than the Competition 195's. Always liked them too.
Your application is closer to mine. Last engine only had 255 Max port CFM (or 267 depending on the air flow bench used) and would go to 7k far too easily. That's despite a cam with only 236@.050" which should be all done well before 6500.

 

i am still curious if low lift flow really means anything anyway. Havent seen it definitively tested. I can see it helping during ivc, inertia ram cyl filling. But then again cam timing has to coincide. Idk

 

Apparently it is and as you suggest, has to be tied into cam timing as well.
​​​​​​Here's a link to very lengthy read in an interview with you know who. I doubt many will read it to it's fullest however it does demonstrate the value of low lift flow and how it relates to power production.
Does it matter much for the average build? It's up to the builder to decide that. Does it matter if you're stuffing two atmospheres of pressure into the cylinder? I would think not as much.



https://www.speed-talk.com/forum/viewtopic.php?t=26943

The good stuff starts in the 4th paragraph.

 

These are the one's I ordered (talked to Scott at Extension 124 - nice dude):

https://www.airflowresearch.com/195c...cylinder-head/

They are indeed the Street Eliminator 195's with the upgraded springs and the center bolt VC machining.

My converter/trans is non-locking. And I'm running 3.70 final gears so my RPM is pretty high.

GD

 

I think they changed their springs up slightly. The PN# on the website doesn't match what I ordered.

Mine was the AFR-8019 springs, which are PAC springs. I opted for the titanium retainers upgrade.

• Hydraulic Roller Spring 1.270 O.D.
• Premium Grade Chrome Silicon
• 155 lbs. on seat
• .650” max lift
• Max RPM 7000-7200

 

What's the installed height to get the 155 on the seat? Any spring rate listed?
Reason I'm asking is because it may lead into what's wrecked my current lump. This is what COMP's 26918 specs out at:

I took that to 7000 once or twice (or more) with their XR288HR cam and 1.6 ratio rockers. I think it's safe to say that may have exceeded one or more recommendations.

 

You can find the specs here.

155# @ 1.81”
448# @ 1.16”

https://www.airflowresearch.com/content/sbc-heads.pdf

 

Scott mentioned that they were the 8019 springs - the numbers on the web site are some kind of stocking number or add-on for the cylinder head part number. The actual spring part number is 8019

I opted to not go with the Ti retainers as they will wear and require periodic replacement. Probably wouldn't be an issue but I do daily the car and I won't be taking it past 6500 on this bottom end.

GD

 

I’ve been 7000 on them 8019 springs shimmed around 1.775-1.78 so i think around 165 seat. .603/.613“ lift 230/245 cam

the right lobe And light valve they will go very high. 8000 on lsx hollow valve i would say

 

Should I go to 1.6 rockers? Obviously the springs can handle it. Probably won't make a significant difference but I'm there and I will be ordering new pushrods anyway.....

This is the article I referenced with respect to the 45-57 HP increase over the iron Vortec on the 350..... The dyno charts are neck and neck till 3900. Will be interesting to see if I have to make any really significant changes tuning changes with the AFR's below 4000 RPM.

https://www.hotrod.com/articles/hrdp-0808-comp-cams/

GD

 

More lift, greater valve acceleration, all good things.

The only difference between your valve train and mine is that I opted for the Titanium retainers and my car zings to 7k every time I get the itch.

1.6's will be good for you, and you won't be revving it out to 7k. Honestly 6000-6200 is probably as high as you'll really need to take it.

 

The cracking rate is exactly why I did away with Vortec heads for my 383 build for my Express van. I overheated the Mexican 062 heads to ~250 on the OEM gauge a couple of times and had cracks in both. Had previously swapped them out but frequently spinning 6,200-6,500 rpm hurt the stock L31 bottom end.

I am going for 500 crank HP with a 218/228 @ 0.50, 110 LSA cam and a heavily ported L31 intake. 11:1 383 on E85​​​​​​. Peak should be around 5,500 rpm, highest I should have to spin is 6K and I will probably shift it at 5K in Tow/Haul with the travel trailer behind it. Peak torque should happen down around 3,000 rpm, thanks to Rhoads V-Max lifters. Stall speed is 2,800 rpm and swapping from 5.13 to 4.56 gears with LT285/70R16 tires.

FWIW...1.7 roller rockers making 0.578" lift. on heads that flow 291 cfm @ .500.

I still expect it to run low-mid 13s full weight at around 100 mph. 400 hp at the tires and 6,500 lbs.

My springs are 175# on the seat and 400# @ 0.600".

 

FWIW also taking care of the overheating issue. Every inch of hose will be silicone and I just got a radiator with a 34"x19" x 2 5/16" core, matching fan shroud and Flexalite Flexwave 16" fans that pull 3,000 cfm each. Also picked up a larger trans cooler that is 2x as thick as the stock one. Trans cooler is 8.5" x 11" and nearly 2" thick.

 

Sorry to hear about the cracked head, but you’re going to love those AFR195s!!

As others have said, you’re looking at gaining about 40HP with just the heads. You’re going to drop about .5” vacuum with the AFR – the engine is an air-pump, so the larger valves and increased flow is going to act like you’ve added a few degrees larger cam.

As others have already said, 1.6 rockers will help, adding about an additional 10HP due to taking advantage of the higher lift flow of the AFRs. However, with your split pattern cam, I’d just get 8 and add them only on the intakes. Putting them on the exhaust with your cam and the AFRs won’t add any power and drop your vacuum another couple tenths of an inch.

I wouldn’t change the cam (again, as others have said), a single pattern or small split would work better with the AFRs and FIRST. However, you would only be looking at maybe 10HP over your cam and the 1.6s on the intake – that is to stay around the vacuum you have now without losing anything on the lower end.

 

Whatever you end up doing for a rocker ratio, be sure you have the rockers you want before measuring for pushrods. Just in case you were thinking otherwise.

 

My take on cams. When you have better than 75% I/E a single pattern cam is the way to go. 99% of the street stuff would run better with a single pattern cam. Take advantage of the smaller exhaust lobe by tightening the LSA slightly to give you the same overlap of the dual pattern and it will be stronger at every rpm point under 4,500.

Also if you compare bigger port, smaller cam to smaller port, larger cam the larger port, smaller engine will have better manners everytime with similar power output.

 

So lets say I were to change the cam - not lose anything significant on the high end, but wanted a little better idle quality. Any suggestions?

GD

 

100% total agreement

 

What muffler are you running?

 

faster acting lobe, maybe abit more at .050 duration wise but not too much more. Maybe abit less exhaust duration 4 deg split. Keep lsa in the 112-113 range for idle. Icl in earlier 108-110 icl. More lift lobes like xfi. Could give abit more overall average power

intake exhaust ratios also don’t necessarily matter. Some ls cathedral head cars have high exhaust intake flow ratios 75+% and make better power with split duration cams.

 

Top-end HP most engines make more power with a dual pattern cam. ~6,000 rpm street engine that rarely sees the high side of 4,500 rpm, not likely to happen. The single pattern cams usually make more average power throughout the whole pull.

 

Personally I would switch the cam up a little.

Use the XFI lobes designed for 1.6 rockers.

Use the 268 @ .006, 218 @ 0.050 lobes that have ~.570 lift.

268/268 @ 0.006
218/218 @ 0.050
.570/.570 lift
108 LSA
104 ICL

More aggressive lobes with more lift, less duration to boost cylinder pressure and the higher flowing heads. Should give a substantial power gain EVERYWHERE and the idle will be tamer than a LT4 Hotcam or your old cam.

The old Slegehammer 350 build used 224/224 on a 108 LSA and with heads flowing 250cfm made peak power at about 6,400 IIRC. With the LTR of the FIRST I would shoot for peak about 5,600-5,800 and it should stay strong up until about 6,000-6,200.

Beauty of good flowing heads is the cam can be tame and you can still have great hp. I think anthing more than about 218° intake duration and you are shooting yourself in the foot with the LTR intake.

 

Geez Orr. Your starting to sound like David Vizard! That spec looks like something straight out of his Torque Master program. Nice spec too.
With a 250 CFM head and 10.4 CR it gets me to this posted below. Not too dissimilar except the added CR compared to GD's 9.7 (?) allows for a little more duration. Note that it lists the minimum suggested lift figures. The higher you go with the AFRs the better obviously. My heads are a little lift vs flow limited in comparison.

 

Except those were not Orr's specs. Those are the ones I came up with.

 

Sorry about that Fast (I was in a hurry when I posted that). Props to you then. Not to take anything away from Orr. He knows his ***** too.
Not sure, what's your take on the way Vizard spec's a cam? He's certainly a master but not everyone digs what he dishes out. But what you proposed is a typical DV result. Namely the tighter LSA.

 

Couple things – I ran a 218/228-110 cam in a flat top 355 with lesser heads and a FIRST. I was able to pull over 18” of vacuum. All the cams I ran in the simulation should pull more vacuum than what I ran and what you’re running now.

The cam you’re running now isn’t all that bad and has a pretty good rate of rise - the XFI’s are just a little faster but the main advantage is the extra lift they can provide. All the simulations are using the XFI lobes (218/218 - 108, 222/222-110 and 226/226-112) with 1.6:1 rocker arms except yours, which is the one labeled 113. With the wide 113 lobe spread you have now, any cam with a tighter lobe spread that can keep the top end you’re making now isn’t going to idle much better with only a 0.5” increase in vacuum, which is about what I figure the cams in the simulations will give you.


As you can see, the 226/226-112 (1.6 rockers intake/exhaust) adds a little everywhere (about 6lb/ft and 7HP & 0.5” vac) over what you’re running now (with 1.6 rockers on the intake side of your cam) but it’s not all that much considering the cost involved. The 222/222-110 +4 would be within 6HP on the top-end compared to what you have now and give about 20lb/ft at 3,000 (and under). That would be noticeable in throttle response, but with your stall speed, gears, and the FIRST I’m not sure you need any more than what you would have with the cam you have now. If your bottom end was good before with the Vortecs, I'm pretty sure I wouldn’t want to give up anything on the top end - even though you'll be gaining a lot with the AFRs over the Vortecs.

I added a line on the simulation at 3700rpm which would be about your shift recovery RPM going into 3rd gear. Looking at that, the “winner” to me would be the 226/226-112 - it’s not a lot of gain, but it is a little better everywhere and would make a little more vacuum. Not sure it would be worth the cost of the swap unless you think you could get a decent price for the cam you’re running now.

I’d lean more toward sticking with what you have, adding 1.6:1 rockers to the intake valves, and depending on the muffler you’re running now, possibly upgrading it. Plus, didn’t you mention nitrous? Even the 108 spread with 218 degrees duration would be OK with nitrous, but the extra spread on the exhaust on what you have now would be more favorable to the nitrous.

 

I have the Flowmaster American Thunder on there (was free of one of my parts cars). Dyno Don headers and matching catless y-pipe.

Very interesting results. Not gigantic differences between any of the cams. Since I have the 1.5 rockers I do like the idea of just getting eight of the 1.6's for the intake valves.

Got one head off today. Not cracked that I can see. Definitely a blown head gasket on cylinders 2, 4, and 6. Not sure what to make of that exactly. I threw a straight edge on the head and block and both are still completely flat with excellent surface finish. Bolts were all tight, good sealant on the threads. Perhaps the high EGT's from the lack of timing incident caused the head to pull away. I am going to upgrade to actual ARP bolts rather than the Summit brand head bolts I used.....

GD

 

I was hoping it wasn't the 80 series Flowmaster. It's definitely going to hold you back. Here's a link to one of my old posts on the 80-series. https://www.thirdgen.org/forums/exha...ml#post6160865

You really need at least a single 4" system for your power level. If you don't want to replace the whole system, at least get one of the Ultra Flo (part # 17227 - $123) or one of the MagnaFlows (part # 12267- $132) – both have a single 3” inlet and dual 2.5” outlets.

I ran a 17227 on about a 415FWHP/330RWHP combo - it did OK for me on motor, but on the button it literally whistled. I was going to step up to a single 4" pipe and single in and out muffler, but ended up selling the car.

Also check to see what if any overlap you have with the headers and exhaust port. If Dyno Don used an oval flange instead of a "same as port" (SAP) type flange you might want to bevel the edges on the flange where there is overlap. Pretty sure the AFR heads have a raised exhaust pipe, so be aware that it might lift the crossover pipe high enough that it might be too close to the oil pan or come into contact with it. If it's really close, I've used header wrap to help mitigate the heat transfer to the oil pan/oil.

 

I take it these are COMP's XFI lobes and you'd get a custom grind? Just looking for the full lobe profile in the COMP Lobe Index.



Came across this regarding Dyno Don headers and a D shaped exhaust port. The picture is of the Dart 215 although I believe AFR has a similar shape.

 

Afr dont have d ports so it shouldnt be an issue, but gasket matching or overlaying should be checked to make sure you seal the port area well. Dont cover the exhaust port and it should be fine

i did have to mod the y pipe and cross over with a set of afr 180’s on a L98. Hit the pan so had to make an extension piece. Was easy.


duration is just time. Long runner intake, air travels farther so needs more time to fill cyl for a given rpm. So dont be afraid of adding some duration for power production even at a limited 5800-6000 rpm range.

i dont mind a tight lsa single pattern. Tight lsa wont idle as great tho if you dont like chop. It can be as drivable as any cam once tuned but if the lope annoys you, then you need wider lsa and or mufflers that dampen the sound some. Single pattern would work best on better exhaust system too, shorties and a small single pipe in to 80 series is not ideal imo

 

Yes, the ones I used in the simulation were the XFI lobes. I typically go with custom grinds on mine and most all the builds I'm personally involved in. The profile I end up with varies depending on application/intended use.

Since GD already has a cam that will generate decent results, I'd leave it alone and just add 1.6 rockers on the intake valves.

 

Can't find any cracks in the heads. Not entirely sure what the hell went sideways here.

Observing the head gaskets, it definitely blew from fire ring to cooling jacket in cylinders 1, 3, 2, 4, and 6. It also blew between cylinders 2/4, and 3/5 - which accounts for the excess cooling system pressure and the crankcase pressure.

These were FelPro 1094's - 0.015" compressed thickness. Summit Racing 12 point head bolts which were all tight with sealant intact. All torqued to spec very carefully with a Snap-On digital torque wrench.

I measured the deck and the heads with a machinist straight edge and can't find any warpage at all. Both the deck and the heads were resurfaced to a typical MLS style finish. Very smooth.

So I don't really have a good working theory on the failure. That's a LOT of fail on both sides of the engine so something is fundamentally wrong. Only thing I can think is that these Summit head bolts stretched and the head pulled away - bowing in the center.

Thinking of going with ARP studs and some Cometic 0.023" MLS gaskets with the AFR heads.

GD

 

How are you checking for cracks? Visually? May not see them easily

 

I prefer to run ARP bolts in a stock block unless the customer just insists on it. I’ve sprayed 500hp nitrous on top of a 600hp engine for years and used ARP bolts on others around that power level as well without any issues. I can’t remember the part number off the top of head for the ARP head bolts you need but it’s posted on the AFR website.

 

Mls needs a reallly smooth deck to seal best

 

Yes. Visually. I know they will have to be pressure tested and magnafluxed before they can be declared safe to use again, but the gasket failure is REALLY obvious. Exhaust gas discoloration (black) on both sides of the gasket into the upper water jacket passages, and between the middle cylinders. It is absolutely FOR SURE primarily a gasket failure. Maybe the head(s) is cracked as well but if it is, I can't detect anything in any of the ports or near the valves, etc.

Yes the deck and heads were surfaced by a shop that does all my heads and blocks and all the modern engines we do (lots of Subaru's known for gasket failures) require a surface RA of 20-30 because they all use MLS gaskets from the factory. I have an RA meter specifically because I wanted to check this and the RA is generally around 18 to 22 or so with my meter. The block and heads both had excellent smooth finishes.

GD

 

Any updates on the heads? Are the AFR 195's on yet?

 

They haven't arrived yet. When I ordered I was told 3-4 weeks. It's only been 2 weeks so not expecting them for a bit yet.

GD

 

Are you going to be changing anything else other than the heads? As mentioned it would be interesting to see a dyno comparison between the two.

 

The only other change is to 1.6 rockers. Because I can and AFR confirmed that I would absolutely have to measure for new pushrods anyway. I'm going to keep the cam for a proper comparison.

GD

 

I'm looking forward to the results.
How low will your dyno go? Can you do a pull from just off idle?
As for pushrod length, that's an area of engine assembly that I really fuss over. I'm tired of having to replace valve guides because I was out a tenth or two.