I've read alot about 187s and 193s. That they are garbage. That with work they can produce good results. That they are not the weakest link on a TBI engine.
I'm asking for a guess as to how much horsepower you think they can accomodate unmodified. If everything else on the motor was modified for maximum power, at what point do the bone stock heads become the bottleneck?(more interested in 193s) I say a guess because I don't suppose anyone would have tried this in their right mind. thanks for any replies.

 

I would say, as soon as you change the cam in your motor to anything above and beyond stock (which isn't hard to accomplish) the bone stock swirl ports become a restriction. That can be said about most bone stock heads though IMO.

 

Try a few searches for Fast355. If I recall he was making roughly 300hp and 400+lb ft with mildy ported 193's and a mild cam. There are also a few links in the above stickies that will help explain their limitations as well.

Swirl port heads are not the best but they are not the worst either. Most people miss match cams and skip the tuning required to dial in their TBI system. The exhaust and cam are the biggest bottle necks on these motors. Dewey316 is running 14.5's on untouched swirl ports and Fast355 was running low 15's in a 5200lb van.

 

Lo-tec ran 13.6 @ 101 using a stock 193 swirl port (SP) heads atop a junkyard Caddy LO5 engine installed into his 3rdgen Fcar, per this thread. He did the usual exh mods + cam swap. Dewey316 did something similar with his SP head LO3 and ran 14.5 @ 94. Dewey also dynoed his car and got 208 rwhp. See this thread for Dewey316's post.

Both of these people used stock unported swirl port (SP) heads. If the heads were really that bad, if they were the junk often claimed here on TGO, then neither of these guys would have run that fast.

The truth (based on results from TGO members!) is that the SP heads flow about as good (or as poorly) as the 083 and 081 non-swirl heads, and those heads+engines (on TPI 350s and 305s) also respond the same exact way to exhaust + cam swaps: they make more power. And like the non-swirl heads, the 193 and 187 SP castings (from LO5 and LO3 TBI engines) respond well to porting as proven by at least two TGO members, plus other non-TGOers. The SP heads exhibit fast-burn characteristics (which is good, they don't need a lot of ignition advance), they just need cleanup (like most factory GM heads) to achieve decent flow.

SP heads are not performance heads (no factory pass car street heads were "performance" until the LT1 heads issued) but with a little effort they can perform about as well, often for a lot less $$$ than buying other heads. SP heads are not recommended for a costly engine build (because you can buy new heads that flow well without porting) -- so if you are spending serious money, then you should look elsewhere.

For low-cost builds, or if you already own them, SP heads work fine as is without porting (Dewey's and Lo-tec's cars are examples), and they work even better with porting (Dyno Don, Fast355 examples). From a chassis viewpoint, SP head TBI 350 have approached the performance level of stock LT1/L31 heads, as evidenced by Lo-tec and Dyno Don's 3rdgen track data; they're on-par with a few Vortec L31 350 3rdgen owners here, i.e. mid 13s in the quarter mile.

Lo-tec's apparent use of a carb (he did say low tech...) seems that it made up for using stock SP heads, while Dyno Don used ported heads but also ran them with a TPI, so the upper rpm range would have been flow limited by the TPI. Fast355's testing is probably the best overall example (head flow data, dyno data, track data) but he ran in a 5300 lb G20 van, so a few people here have difficulty appreciating a 15.7 sec quarter mile result because it wasn't in a 3500 lb 3rdgen Fcar.

IOW all three examples could have run faster (Lo-tec with porting, Dyno Don without the TPI, Fast355 in a 3rdgen), so there is more to the story.

See Fast355's thread on garage ported 193 castings. It contains both opinions and facts. You just have to decide which is which. HTH.

 

thanks, that does help. I'm going around in circles right now trying to figure where i'm going to draw the line on spending vs power vs driveability. I recently aquired a set of 193s that are ready to bolt on. if i extrapolate Dewey316's numbers (he's 22% over stock 170hp) to a 210hp LO5 i get 256hp. i would assume that Lo-tec is exceeding that number.

 

Dewey measured 208 rwhp, and the GM flywheel number is 170 hp stock. At the risk of incurring the ire of the powertrain loss critic, if I assume 18% loss then Dewey would have been making 254 fwhp (flywheel hp). That's 49% above stock (254/170).

Lo-tec's 13.6 @ 101 is in the performance range that a 4th gen Fcar (with LT1) would run, so that puts his engine at 275 to 285 fwhp and probably no higher (due to the 101 mph trap speed). Since Lo-tec ran MUCH quicker (with a 350) than Dewey did (with the 305), then I would expect Lo-tec's torque output to be much better than a stock Fcar LT1 (325 ftlb at the flywheel).

The power to cubic-inch ratio (say 280/350, or 0.80) for Lo-tec's engine is not quite as good as Dewey's (254/305, or 0.83) which probably means that the stock unported 193 heads on the 350 are slightly more of an airflow (and power) obstacle than the stock unported 187 heads are on the 305.

If you read the garage ported 193 thread, Fast355 was making a peak of 279 rwhp (which means 330 to 340 fwhp) so the power/cid ratio is darn close to one (335/355, or 0.94). IMO his 2-bore stock-sized TBI was a flow obstacle at those power levels, so I think he could have made more power with a bigger TBI and using the exact same engine beneath it.

In re spending vs power vs driveability, IMO the best choice is to make the heads flow as well as possible with DIY porting so that you can use something close to the stock cam, or no warmer than the Fcar LT1 cam. My reasons are that the combination will give the best fuel economy, the best part throttle driveability, and very good top end power, for very little cost. That approach minimizes the spending, gives good power, and gives awesome driveability.

Lurking beneath this entire discussion is the assumption that the ECM (and EPROM) are optimally tuned for the engine it's attached to. HTH.

 

>>>In re spending vs power vs driveability, IMO the best choice is to make the heads flow as well as possible with DIY porting so that you can use something close to the stock cam, >>>


Well I guess I'm going to give it a shot. That is I'll try a safe moderate amount of "cleaning" them up and see how it goes. I intend on using them on a 400 I'm preparing to assemble and run TBI so I know I have alot of details to work out. But I'll stay on the topic of heads for now.
Is there any problem with drilling the steam holes on these heads that anyone is aware of?
These heads are said to be 64cc chamber volume. Has anyone checked this?

 

Since my car has become part of this topic I am going to jump in.

Maybe JP, fast355, and a few others will also. We have several people on here, with several theory's on swirl ports.

A couple of things.

Yes my car put down 208hp to the wheels, N/A. BUT, that was in fact a disapointing number for a couple of us. #1, we had seen a TPI power 305, with a similar, but slightly smaller cam, put down 223hp on the very same dyno (remeber, numbers do vary from machine to machine). We really thought that I would have a 230hp pull in this motor.

Secondly, the power curve. Don't get stuck on peak numbers, look at where they accured. My HP peak still occured around 4800 RPM. That is darn near where a STOCK LO3 puts down its peak number. My cam specs are 206/216 .447 .447 112. They HP peak should be in the 4500-5000 RPM range on a 350. The cam designer even said on my 305, the HP peak should be around 5800 or so. That never happened. If you look closely at the graph, the torque never really starts to drop off like most dyno readouts, neither does the HP, it just slowly goes down, almost in a straight line, and my HP stay's almost unchanged from 4800-5500 RPM. I actualy think this is the swirlports not flowing the needed air to support the motor at those revs. Hopefully soon I will have some port 416's on this motor, to really compare. I have every feeling that a 230hp or more dyno pull is in here, with nothing more than a head swap, and the proper tuning.

I would be very interested to see some of the other dyno graphs from other buildups with larger cams, and swirl ports. I bet we see them also top out the HP in the 4500rpm range, just like mine does, and just like the stocker does. In a 400ci motor, I bet it chokes it down even sooner.

 

My G20 is part of this conversation apparently., thats cool.

My peak of 279 HP was made with alot of vacuum under the TBI. Later logs showed as much as 4-5" of vacuum building up under the TBI by 5,000 RPM. Not cool

My current 312 is making more HP but less torque and doing it with alot of vacuum under the TBI.

My old 245 RWHP 305 was making 2" hg of vacuum by 3,800 rpm. That is with a ultimate TBI moded TBI, CFM-Tech spacer, Hypertech Powercharger, injectors spaced up, edelbrock intake, and an open element.

My datalog w/ 245 RWHP 312 w/ 3.08 gears(on a steep on-ramp, very heat soaked, loaded, with the A/C on, Ector to 183 going west in Euless).

SPEED---TPS-------RPM--------MAP-------BLM
37-------(-1.2)-----1050--------31.8------118
35-------(-1.2)-----1000--------32.5------117
34---------2.1------1025--------38.8------116
34---------7.9------1550--------50.2------128
35---------8.4------1575--------49.1------127
35---------8.4------1600--------48.4------126
36---------8.4------1550--------48.4------126
37---------8.4------1675--------46.5------126
38---------8.4------1600--------46.1------126
39-------12.3------1800--------53.2------125
41-------18.1------1175--------80.8------108
42-------30.4------1275--------90.4------112
43-------47.5------1325--------96.7------115
45-------71.2------2175--------71.2------119
46-------99.6------2575--------97.4------119
49-------99.6------3550--------95.2------119
53-------99.7------3775--------94.9------119
56-------88.1------4100--------94.9------119
58-------58.6------2700--------93.1------119
59-------44.1------2175--------90.8------121
60-------40.3------1650--------91.5------125
60-------37.9------1675--------90.4------124
61-------21.9------1650--------74.2------125
60-------20.5------1675--------62.3------127
60-------15.7------1675--------63.1------128
60-------15.7------1675--------62.3------128
60-------15.7------1650--------62.8------127
60-------15.7------1675--------63.5------128


Dewey are you sure your heads are it and its not the TBI restricting your power. Also what size are your injectors and what pressure are you running them at. Notice the very wavey curve after about 4,500. Are you sure you are not going static or near static? Maybe you are simply out of fuel. To make 300 RWHP I am runing 350 injectors at 32 psi/22 w/vacuum. To get 245 I was running the same regulator and pressure just 4.3 injectors.

Also FYI from experience a cam is really no different between engines. The 305 and 350 have different cylinder volumes but also have different valve sizes and sometimes port sizes. The same cam will behave about the same in the two. You won't see any more RPM on top of the powerband to speak of out of a 305 vs. a 350 with the same cam. The cam is rated 1,800-5,800 on a 350 it will pull from about 1,800-5,800 on the 305. Take what the cam is rated for and apply it to the 305, your peaks will be about where they advertise them. My L82 cam actually peaked torque wise a little sooner in my 305 than it did in the older 350s.

 

You're comparing a TPI result to a TBI result. Remember that Dyno Don did a TBI vs TPI test using the exact same cam, same block, same heads etc (i.e. it was the very same engine in the same car) beneath these two different intake/FI systems. So it was aimed at the TBI vs TPI question, and NOT directed at answering "which head is better?"

IIRC the TPI system made 18 rwhp higher than the TBI did. The tests were done in different months so IMO the weather (air temp) might have effected the results by approx 3 hp, so the difference might have only been 15 hp.... but the TPI still would have had the greater output. So given Dyno Don's result, I attribute at least 15 hp of the comparison you made to the TPI being better (in stock form) than the stock TBI. 208+15 = 223, which is about what you had observed from the TPI engine.

This thread has the links to the original post on the TPI-TBI comparison.

Quote:

Secondly, the power curve. Don't get stuck on peak numbers, look at where they accured. My HP peak still occured around 4800 RPM. That is darn near where a STOCK LO3 puts down its peak number.

Actually 4800 rpm is not close to where the stock LO3 peaks in power output. Here's one of many online GM sources for LO3 specs, this one is from 1991 as used in the Caprice copcar (9C1):

http://www.9c1.com/brochures/1991/91_9c1.pdf

it's 170 fwhp @ 4200 rpm as measured on an engine dyno. The copcar LO3 is identical to the LO3 used in your Fcar. Same heads, same cam, same TBI. When it's measured on a chassis dyno (in the car) the peak power output usually occurs at an rpm less than the one obtained by the manufacturer because the drivetrain losses increase with increasing rpm.... so the power peak migrates to a (slightly) lower rpm.

Example of a stock LO3 test here. The power peak occured at 3700 rpm in the car on the chassis dyno.

So your exhaust+cam modded LO3 peaking at 4800 is, IMO, sensible.

Quote:

My cam specs are 206/216 .447 .447 112. They HP peak should be in the 4500-5000 RPM range on a 350.

That cam is slightly warmer than the LT1 Fcar cam, and the LT1 Fcar engine peaked at 5200 rpm on the engine dyno, and around 5000 rpm on the chassis dyno on a 350. BTW those numbers are both achived when A.flowing through heads that can support over 400 fwhp with ease, and B. flowing through an intake manifold that can support whatever the heads want. You don't have those heads, or that intake, so I wouldn't expect your engine and your cam to have peak power at the same rpm, because of the airflow impediment of the stock heads and maybe from the TBI itself. I also don't think your results would have been any different if you had used unported 081 heads from a 305 TPI, and I doubt the results would have been much different using unported 416 heads (which flow better on the intake, but worse on the exhaust).

So I don't expect your cam to peak in power at, or above, 5000 rpm on the chassis dyno for the reasons given above. 4800 rpm is sensible because of the stock heads. That's why I said that you got good gains in power from the exhaust + cam, but if the heads were really as bad as claimed, I doubt you would have had the dyno and track success you've had. I don't expect miracles from any unported factory iron heads (prior to LT1 vintage), and I do expect significant improvement when/if you do port them.

Quote:

The cam designer even said on my 305, the HP peak should be around 5800 or so. That never happened.

The cam designer was wrong. 5800 is a looong way from 4800-5000 rpm. Your cam is slightly warmer than an LT1 Fcar cam, and you aren't breathing through an LT1 intake nor LT1 heads. So how can your engine power peak at 5800 rpm when the LT1 Fcar engine doesn't? It can't on your engine with your mods --- and the cam designer was wrong, or used the wrong input data for head + TBI flow.

Quote:

If you look closely at the graph, the torque never really starts to drop off like most dyno readouts, neither does the HP, it just slowly goes down, almost in a straight line, and my HP stay's almost unchanged from 4800-5500 RPM.

That's the same generic behavior of a TPI intake, when it becomes airflow starved. But be fair about it --- it did peak in power at 4800 rpm, rather than at (or under) 4000 rpm (per the thread I linked above for the stock LO3 dyno data).... so even if there was an airflow limitation, you did gain nearly 1000 useable rpm and the torque & power that goes with them. IOW a very useful gain.

If the heads were as bad as claimed, would your rpm for peak power have moved to 4800 rpm, and would you have gained 63+ hp at the rear wheels (using 145 rwhp stock) from the exhaust + cam swap? Would Lo-tec have run 13.6 @ 101.5 mph using a LO5 350 similarly modified as your car? Your gains, and his gains, are no different than the gains made by people with stock unported 081 (305) and 083 (350) heads. So the SP heads aren't really any better, or worse, than the non SP heads in stock form. Neither the 187/193 SP heads, nor the 081/083 non swirl heads, are performance heads. But both can be made to run well by altering the exhaust and the cam, as proven by many (including you).

Quote:

I actualy think this is the swirlports not flowing the needed air to support the motor at those revs. Hopefully soon I will have some port 416's on this motor, to really compare. I have every feeling that a 230hp or more dyno pull is in here, with nothing more than a head swap, and the proper tuning.

I don't doubt you will see more power, and a power peak that moves to a higher rpm, if you use ported heads.... any ported heads.

Quote:

I would be very interested to see some of the other dyno graphs from other buildups with larger cams, and swirl ports. I bet we see them also top out the HP in the 4500rpm range, just like mine does, and just like the stocker does. In a 400ci motor, I bet it chokes it down even sooner.

The stocker doesn't peak there, especially on a peanut cam LO3. Peak power is 4200 rpm on the engine dyno and under 4000 on a chassis. The LO5 police TBI engine (which uses the L98 cam) peaks at 4400 rpm (engine dyno) and just above 4000 rpm in the car (chassis dyno).

IIRC Fast355 peaked in power at 4700 rpm using the LT1 Fcar cam in a 355. I commented that I thought his stock TBI was causing an airflow starvation problem for him because the tiny 42.6 mm dia bores of his stock TBI aren't really suited to move enough air to support over 310-320 fwhp. Since he made 279 rwhp @ 4700 rpm, then he probably was making over 330 fwhp @ 4900-5000 rpm.... and with that cam and his ported heads, he should have peaked in power above 5000. I don't think his (ported) head flow could be an impediment to lower the rpm for peak power, but the stock TBI would.

In your case -- the hp output is much lower than what Fast33 had so I doubt the TB is the cause; for you I would believe that the heads are now limiting the output, but I don't believe that the heads are the limiter on the stock engine --- because --- you wouldn't have the gains you observed if the stock heads were a flow impediment with stock heads + stock cam. You are NOW at the point where they probably are flow impediments and likewise for Lo-tec's 350 with stock SP heads and exhaust+cam swap.

EDIT: I noticed that your AFR went lean and crept above 13:1 past 5200 rpm. You might have made slightly more power there had you kept the AFR under 12.8... but not likely more than the 208 peak hp you observed.

 

I'd check with the Tech Engine board here by doing a search for 400 sbc and/or steam holes. Make sure any holes you drill, plus the ones already there, are smooth and have radiused edges. It reduces any tendency for a crack to start.

I haven't check the 64 cc on 193 heads, but I have read it in several places and know someone that's measured it at 64 cc. HTH.

 

I should be able to provide some interesting data in a week or two. I'm throwing in a completely stock L03 long block with a LT1 cam, rpm intake, 454 TB, and free flowing exhaust (better than most thirdgen stuff). I'll be able to get some g-tech pro HP curves. Of course the actually numbers won't be worth a crap, but where it peaks will be interesting. I've removed every restriction on this motor other than the heads, the cam really should peak higher than it did in the 5.7 LT1 as long as the heads don't restrict it. It'll be interesting to compare VE curves between this motor, TPI and LT1 motors.

 

kdrolt, I'm not going to do a line by line quote of all that. But, CAMs on a 305 do act larger than in a 350. Call any cam manufacture and ask them about that. There is a reason they always recomend a smaller cam for the purpose on a 305, than they do on a 350. My intake is not the restriction, was at 102kpa when I hit that HP peak, the lowest I have ever seen is 98kpa, and that was darn near 6k, just to see what it would do.

It is not static, I have the pressure cranked way up, I was at a max of about 80% DC on that dyno run. It did creap up on the AFR, because as we know, tuning these cars at WOT is a bit tricky, I made changes based on that output, and then also using a LM1. I had about 20 minutes with an LM1 prior to that run, so I had not had a great chance to nail the WOT tune before the dyno. BUt as we both now, a few 10th's on the high end would not have made a significant change in the powerband.

As for my comparison with the TPI car, my TBI **should** have the advantage on the top end of the pull, the resinance starts to work against the TPI motor, he in fact actualy had a later HP peak than I did, with a smaller cam. His HP peak accured at about 5300. With my single plane intake, My motor with a larger cam, should have peaked above the point where his did. It did not. That tells me that there is a restriction. The sensors tell me it is not the throttle body, knowing the intake I'm running, I think it is safe to say it is not the intake. My exaust was hooker headers, a 3" Ypipe, and then dumped out a cut-out, so that was not the restriction. That leaves the heads to be limiting my power output.

 

That's fine, what I wrote was comments with justification for the comments, not just my personal opinion... but it wasn't me that made the cam behavior comment -- it was Fast355.

I do agree that cams feel "hotter" when used on a smaller engine (e.g. an LT1 cam is hotter, higher rpm for peak power, on a 305 than on a 350).

Quote:

My intake is not the restriction, was at 102kpa when I hit that HP peak, the lowest I have ever seen is 98kpa, and that was darn near 6k, just to see what it would do.

I didn't think your TBI and your intake were restrictions after the exhaust + cam swap ---- I said that already. I think the heads are, but only after you did the mods, not before. For Fast355, with ported heads, his TBI is a restriction.

Quote:

... It (the AFR) did creap up on the AFR, because as we know, tuning these cars at WOT is a bit tricky, I made changes based on that output, and then also using a LM1. I had about 20 minutes with an LM1 prior to that run, so I had not had a great chance to nail the WOT tune before the dyno. BUt as we both now, a few 10th's on the high end would not have made a significant change in the powerband.

Yup, and I'm not complaining about any of it --- I'm just discussing it.

Quote:

As for my comparison with the TPI car, my TBI **should** have the advantage on the top end of the pull, the resinance starts to work against the TPI motor, he in fact actualy had a later HP peak than I did, with a smaller cam. His HP peak accured at about 5300. With my single plane intake, My motor with a larger cam, should have peaked above the point where his did. It did not. That tells me that there is a restriction. The sensors tell me it is not the throttle body, knowing the intake I'm running, I think it is safe to say it is not the intake. My exaust was hooker headers, a 3" Ypipe, and then dumped out a cut-out, so that was not the restriction. That leaves the heads to be limiting my power output.

I agree that the heads, stock unported heads, are a restriction AFTER the cam + exhaust swap you made. I think they still would have been the restriction with stock 081 heads tested under the same circumstances.

On the TBI-vs-TPI: it seems TBI owners all think that the TBI ought to out pull the TPI at high rpms (i.e. make more power for equal engine sizes) but that's not what was shown by Dyno Don's test. And it led to an extensively long and predicatble argument/discussion between TBI and TPI owners. Still, it was the best back-to-back test made on TBI vs TPI that anyone on TGO had ever done, so I'm mindful of it and it does have bearing on your comparison (your TBI to the other TPI).

On the TPI engine that you were comparing with, if he made more power at 5300 with a smaller cam, then it only further supports the results of Dyno Don. TPI engines don't generally peak in power above 5000 rpm (due to the flow limits of the runners) even with the smaller cam yet your friend's car did, so there's an issue there that I can't explain.

 

There is a lot that can't always be explained. And I think that most of us are probably on the same boat as to several thing working between my combo, fast355's, bmontess, dyno-dons comparison, and the many diffrent TPI cars I have dyno'ed.

My only real point in posting, is to possibly save someone from waisting their time on something they will never be happy with. Luckily for me, the SP's were on the car, only because I didn't finish the porting and machine work on the 416's. So although a little dispointed with my numbers, it was a good learning experiance.

Now, had I built my motor around those heads, paid a couple hundred dollars for machine work to have screw-in studs done, maybe bigger valves, etc, then I would have bene extremely disapointed. I really cannot recommed anyone using swirl-ports for a "performance build-up" and especialy could not recomend spending money on them.

The good:
The good news is that, as a couple of us have show, with a few minor modifications, you can make some descent power with your TBI car. I do think mine is a prime example of bang for the buck. And off hte shelf comp/crane/lunati cam of similar size, maybe even just a hair larger. A single plane intake, and exaust. Is all it takes. If you shop around, and don't pay for some of the extra's I did (JetHot coated exaust, etc), you can replicate my combination for aroun $500. At then end of the day, we are talking 50hp or more for $500, the other bang for the buck build-up that can touch that, is N20.

 

Edit: Dewey summed it up nicely

 

And that's why I already said (in the above):