TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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Ok now for part 3, In this installment I have further ported both the intake and the exhaust ports, as well as done a valve job on the intake. Time did not allow a valve job for the exhaust so expect further gains there. The porting consisted of extensive bowl work, , substantial profiling of the valveguides, further opening up the pushrod pinch area, unshrouding the valves slightly, matching to a felpro 1205 intake gasket, thorogh polish of the exhaust, slight polish on the intake (need to keep the mixture stirred), raising the roof of the exhaust port .1 inches and opening it considerably, also some blending of the valve ridge. A lot of reshaping of the entire port was done here as well. The valve job consisted of a standard 3 angle valve job and a 10 degree backcut on the intake valves, exhaust valves were not touched. I also polished the chambers, though this won't affect flow, it will make the heads less detonation prone.
numbers are:
Lift Intake Exhaust
.1 63.8 41.4
.2 120.6 88.2
.3 178.9 124.1
.4 215.2 154.3
.5 240.1 171.8
.6 241 180
As you can see these numbers are substatially up from stock across the entrire lift range, and a significant improvent from stage 1 porting. we are still arunning a 74% intake/exhaust percentage, which is good, though not excellent. These nubmers put us up 47.4 cfm on the intake and 62.4 on the exhaust. The exhaust is right at what I set as a goal (with once again a bit more to come with a valve job) the intake is 13 cfm short of the goal. I ahve not cut for larger valves yet either. Also these are the stock valves, not the ones with a high flow design, so more gains could be found there. According to Superflow we are running over 90% of the flow potential of these heads with these valve sizes on the intake which is excellent and almost 100% on te exhaust which is incredible. For comparison I am attaching a flow chart from the afr 190 heads. As you can see the numbers are getting close. Right now these heads will support 490-500 hp NA.
Things yet to come:
Pictures!! Took some 35 mil shots, digital still screwed, soon as I can get them scanned I'll get them in.
Exhaust valve jnob, maybe the expensive valves.
Larger valve size (maybe, haven't decided yet) I'l probably do this, but only if time allows. It's also something you can't do your self if you don't work in a machine shop.
I might also be able to do some more short side work, not a whole lot though.
All in all maybe another 10-20 cfm depending on what i do.
Conclusions:
The often debated point is whether these heads are worthe working on, at this point I'd have to say the answer is a definite Hell yes, they now way outflow the aluminum L98 heads, performer and performer rpm heads and e-tec 170's, dart iron eagles(small version), vortec heads, well pretty much everything with an intake size of 180cc's ore less, and are right up there with most aftermarket aluminum heads in the 180-200cc range, compare at www.chevyhiperformance.com.
At this point though you better be prepared to do some work and/or spend some money, but you've got the bragging rights of being able to say you did it with stock heads and they're a hell of a lot cheaper than a set of AFR's. The flow velocity on these heads is excellent right now as well, so you'll still get good low end torque.
The down side is that now if you were to pay someone else for thsi porting work your into the $450-550 range. Add new valves and watch the price climb. BUT if you can do the work yourself you have a kick *** set of heads for chump change.
I may do a stage 4 on this series, I may just stop here, but either way I hope that it helped you all out. Good luck, and remember as always, drive fast and take chances
John
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__________________ 89 Formula 350 406, Miniram, Nitrous SOLD
86 Cutlass Salon Sleeper 455
77 Corvette 406, Superram (WRECKED, ARRRG)
89 Iroc New Project
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Yes, I am interested in Parts 1 and 2, and Part 4 when it is completed. I certainly hope you have kept good notes, since this will make one of the finer Technical Articles on cylinder head porting found anywhere. You should consider compiling notes, charts, diagrams, and photos, then publishing a booklet with templates. I'd order one. (I'm interested in the templates most of all).
You are substantiating what I have been preaching for a long time - that stock heads can be manipulated to produce very good flows and velocities. You have quantified on your bench what I have understood but not been able to prove with my limited resources. Additionally, the back-cut intake valves are also an often overlooked item that makes for some "free/hidden" flow increases that I have experienced.
You've done an excellent job in getting the flow rates very flat across the lift ranges - better than most aftermarket heads.
In a somewhat related matter, I had my first close look at a World Products S/R Tourquer 305 heads this past week, and took a few photos for reference. I was not impressed, since I have ported stock heads that have much larger, straighter, and more regular ports. There is nothing wrong with their heads. There is nothing wrong with their chamber design or valve selection. But stock heads can be made even better, and you've just proven it. I'm sure the World heads can be ported to make similar gains, but as a "bolt-on" there could be a lot better port design. And if you have to port them as soon as they arrive on your doorstep, what's the gain? Why spend $900 on the heads and an additional $550 in porting, when you can start with junkyard heads or your originals with the same result, and pocket the $900? Before the early '80 when all these aftermarket head companies were popping up, how do you think we made power? Stock heads. And there are plenty of 450HP+ SBCs out there as examples, still running with the "stock" iron.
The cost is also quite comparable,even favorable, to aftermarket heads. For a total of around $800 with 2.02/1.60 (or 2.05/1.60) valves installed, you can have superior heads that still maintain good flow velocity. I can get a set of Manley 202/160 Race-Flows installed, three-angle seats, front radiused intakes, and bowl ported at my favorite machine shop for about $350. Half of the porting time is done at that point, and I'm still money ahead.
It sounds like you have the basis for the "ultimate" TPI head to me. At those flow rates, the builder should be able to keep the valve lifts (and ramps) more moderate and really turn some RPMs without fear of valve float.
Please, by all means, keep us informed of your progress. You are certainly the "Head Man", and I kneel before you :hail:
__________________ Later,
Vader
- - - - - - - - - - - - - - - - - - "Everything should be made as simple as possible, and not one step simpler."
It's nice to see some numbers on this project............
I did basicly the same thing to my L98 heads 2 years ago,and had NO IDEA that you could get numbers like that...I was just looking for a little more performance without buying new heads.
The "engine builder/machinist" that did the machining on my L98,ported one of the intake ports with his Verdi and a die grinder to show me how much I could take out.It was quite a bit more than I thought.
After I got it running I noticed I had picked up 400-600 RPMs and maybe more,because I haven't shifted it manually to date,but I'm sure I will on my way to work today............
Great articles!!!!!!!! Thanks,Brian
Looking forward to part 4........................
P.S. The money I saved doing it myself payed for a 2500 stall converter.....
Ok, due to popular demand Part 4 will be coming. I ordered the Manley pro flo valves today and will be cutting for 2.02/1.6's tomorrow, then reprofiling everything and new valve job. I may need to unshroud the valves some more as well, we'll check. Also my buddy's scanning in the pics today, so I'll have them up in the next coupla days as well.
Thanks for the kind words guys. Dunno nuthin' about templates Vader, I'll see what I can do for ya. The guy at Manley says that the valves will really pump up low lift flow, and make around 3% at the higher lifts, guess we'll see.
__________________ 89 Formula 350 406, Miniram, Nitrous SOLD
86 Cutlass Salon Sleeper 455
77 Corvette 406, Superram (WRECKED, ARRRG)
89 Iroc New Project
ive been working on mine in free time since just before you started your project. they are comming along great. i have manley race flo valves 2.02/1.60s on mine also. im thinking about getting them milled down to around 60cc for a little compression, but not sure if it would be too good of an idea with iron. we will see though. mine shouldnt be too long before i get them bolted on.
Looks Good. Now I don't know how much more you did after this pic, you said it was during work, but a coupla suggestions. If you've already done them, just ignore it and move on
I did quite a bit more unshrouding along the tall edge of the chamber. 'Cause otherwise you get air hitting the wall and washing down the side of the chamber with fuel coming out of suspension. Use a head gasket to mark the edge of the chamber so you don't go to far. Also I'd cut your valve guides into more of a teardrop shape, you can take a fair amount more material out in the back to make a smoother transfer, you'll see some loss there do to flow expansion and turbulence otherwise (About 4%). You've also got a machined edge between the valve seat and the chamber, if you CAREFEULLY smooth that down to blend with the rest of the chamber you'll see some gains there. Looks like you've got a steadier hand than me though
BTW Vader did you see the article on porting the SR torquers, I think it was in CHP, I was pretty disappointed in they're results.
You should consider compiling notes, charts, diagrams, and photos, then publishing a booklet with templates. I'd order one.
This sounds like the ticket for my car. I am trying to use factory components all the way since this is a daily driver. Thanks for all the information. I look forward to the next installment. Edit: I would also order a "rhuarc30 Guide To Fantastic Factory Flow" if you put one together.
Quote:
You are certainly the "Head Man", and I kneel before you :hail:
Heh, yeah it does sound awful doesn't it. I'm not a very good teacher, so I dunno how good a guide I can put together, but I'll give it a shot. At the very least I'll pull together a list of the resources and articles I learned from. Car Craft had an excellent article a coupla months ago, if I can just find where I stashed it now.
Im up in the air Myself as to wich Heads to use on MY upcoming project, You may be on the way to answering that For me, And I imagine Many others.
__________________ Ian Moore
1985 Camaro Sport Coupe - TPI
Five Liter TBI Eater -=ICON MOTORSPORTS=- - Motorsports for ignorant people. Need a Custom PROM?
For somebody like me stuck with a limited working man's budget, this info is invaluable. well done. between the siamese thread and your work...just wonder how my 305 mule would respond.. lol, just may have to pull er apart and do some whittlin, cheers, Bob
__________________ 84 SVO 9W HE351 Holset, B234F, custom intake, header, FMIC, MSII, Map Daddy
- my toy 86 Olds 442 403, 200R4, 8.5" 3.73 posi, T-Tops - mmm.. torque
-her toy
Originally posted by Christos This is great stuff, i can't wait for pictures.
No kidding. I am taking my L98 apart next year and would love lead time to prep. rhuarc30, how DARE you have a life beyond getting this info out for the others to see?
Originally posted by rhuarc30 Oh btw the numbers are at 28" of water and .5 valve lift. I'm testing at 6 points from .1 to .6, but the stock heads peaked at .5.
can't wait to see them I just got a set of L98 heads and can't wait to do this to:lala:
__________________ none in still looking here in Japan
See if I can take these in order.
Yes, head man sounds wrong, unless you ask my wife
Christos, yes modifying for the heads for more lift is easily done in a shop, not something you can do at home. You'll have to cut the valve guides down a corresponding amount, then remachine for the positive valve seals. Not very difficult, but requires some expensive equipment and attention to detail, as does the cutting for bigger valves.
Yes, I know, but FORTUNATELY I do have a life outside this Part of the problem being that I have 27 photo's, so the file will be huge :. I'll probably put it up on my site and just link to it. Instructions will be pretty thorough. I thought I'd have it done last week, it may be next week, but the photo's and last installment are coming up. I've also been using this as a tool to train a new kid, so I have some pic's of where not to screw up that I'll include as well. As a preview the final numbers @ .6 inch lift are 265/192 with 2.02/1.6 and the Pro Flow valves. The lowlift numbers are improved as much, if not more. Keep in mind, I've done a lot of this, and some of the work you'll have to farm out, unless you work at a shop. The larger valves alone include cutting for them and installing new seats, not jobs for the inexperienced, and impossible without the tools. Also keep in mind that I get paid for this, and operate a niteclub on top, so the paying customers come first. But by the time I have the photo's and article up I should have some dyno numbers with these heads on a supercharged, solid roller, lt1 intake, 383 that I'm building for the Iroc as well. Should be around 900 hp *pray to the car gods*. BTW the AFR 195's flow 262/192 @ .6 standard, though the competition package goes to 280/208.
__________________ 89 Formula 350 406, Miniram, Nitrous SOLD
86 Cutlass Salon Sleeper 455
77 Corvette 406, Superram (WRECKED, ARRRG)
89 Iroc New Project
If you need space on a webserver for pictures, let me know.
I'm totally new to modifying cylinder heads, how do you learn all this stuff? I see all these terms like short side radius, etc. and it's way above my head. Any good books to read and learn about the theory for this stuff?
I don't know much about heads, just trying to learn more about them.
Would it be better to do this porting job on L98 Aluminum heads or the L98 Iron heads? I know the vette heads flow better stock but after all the porting which would come out better?
tpi_roc, that's a very good link you put up. Too bad I didn't read it
before I ported my aluminum vette heads. I guess I can throw
that pair away now and start over with a different pair.
Are there any certain year/casting ## L98 iron heads to use?
I keep hearing that my 89 iron L98 heads are not very good due to some casting that was supposed to promote swirl. They all say that all it promoted is an airflow/power limit.
__________________ 1989 Formula 350 / Dual Cats / Nine Bolt 3.27 Posi / 4 Wheel Discs
9.50 @74.5 mph in 1/8th at 73,000 miles - Bone Stock
9.50 @73.97 in 1/8th at 145,000 miles - Still Stock (except for K&N Filter)
9.44 @73.99 in 1/8th at 147,000 -Hooker 3" Cat Back Kit & Lakewood Lower Control Arms
9.24@75.44 in 1/8th @ 148,000 - char. cannister, smog pump, & MAF screens deleted - removed spare & jack, & junk (65 lbs.)
8.93 in 1/8th - - 13.89 @99.9 MPH in 1/4 @150,000k - cheap ($80) Summit headers, Flowmaster y-collector, Soon to Come - 1.6:1 roller-tip rockers
Wow - fantastic topic! Count me in as one of the many looking to port their stock L98 cast iron heads, and these 3 installments are a terrific resource.
I too await Part 4 of this ongoing saga. Excellent effort, and thanks!
I know there are two different casting numbers for the cast iron L98 heads. Anyone know the difference between the two? Is there an advantage to one over the other?
