Inliners International Forums General Discussion Engines Bang for your buck I6 mods?

My '64 GMC project is gonna be a low budget primer black hot rod/ rat rod thing.... Tossed around the idea of a V8 for awhile but ordered Leo Santuccis book, I'm gonna do the six. Has the orgiinal 230/3 on the tree.
I already have an HEI and a Offy 4barrel for it, so I'm wondering, If I can only spend say... less than a grand on engine mods to get a little bit of pull out of it, what the best bang for the buck? I've heard the 390cfm 4bbl is a good choice, and will cost $300 or so, Clifford sells headers for nearly $400, summit has a couple sets for $200.... Will the summit ones still be an improvement? People say to go with a mild RV cam.... that will probably be a couple hundred as well..... So if you wanted to get some pep out of the six, and couldnt do all the mods, how would you rate them on bang for the buck? Also would a 194 head bolt on do good as well? And is it crazy to expect 200 ish HP out of the motor with these mods? Thanks, this is the first motor Ive ever modded save for dirt bikes..... Will keep searching but thanks for any input!

Great lookin' little stepper there!

Start with the intake and exhaust, and ignition. Offy is streetable, and the Holley 390 should be great. Check out E-Bay for a set of headers, otherwise keep an eye on classifieds if you don't mind used parts - $400 for a set of long tube truck headers is outrageous, in my opinion. SO yes, the Summit headers will still be a very big improvement over the stock exhaust manifold. And remember to run water heat to your intake for better fuel atomization.

After that, a cam is the next step. You should be able to pick up one for less that 200, I'd think. Check around, a couple cam companies have been goping under, but last I checked, I thought Comp and Crane carried I6 cams, however, I may be mistaken. Check Schneider's cam's as well.

And as far as heads, a 194 head will give you almost a full point in compression, which is always helpful. You may be better off finding a good quality head, and start putting money into it after the other bolt ons are done to the engine. Start with valves, lumps, porting and polishing....etc.

But, that's what I'd do. You're off to a great start in the right direction!

-Sam.

Also consider that the difference between a 230 and 250 is the crank shaft and rods. Then look at the thread in the "Hi Performance" Forum, "Dyno day for a 250". The information that will be available will be real numbers for performance mods. Then if you shop around you will find out how much HP you can afford.

I bought an RV cam from J.C. Whitney for about $110 with the ride. It came with a set of lifters, no cam card.

You can also look for an exhaust manifold with 3 bolts on the flange from a 292. This exhaust manifold has a 2.5 in open vs the 2 that 230/250 manifold has. I bought new long tube headers off ebay for less than $100. Patience,,,,

Larry

That GMC didn't come with an original 230 if it was sold in the US.

Oh wow, I didn't even consider that. Durr. *Should've* had a 305 V6 originally, or a 351, but those are rare.

-Sam.

Consider Tom Langdon's headers.
http://www.stoveboltengineco.com/acartpro/product.asp?productid=171

They're cast iron, for longevity.

Also, he's a member of the club.

regards,
Leon

Prior to all the 292 dyno testing we performed this month, it was always assumed the 194 head swap was a viable way to increase compression, and thus HP as well. We have since found this to be an untruth, and actually, HP and torque is lost and not gained by using the 194 head. Even with proper unshrouding of the valves, we consistently saw this to be a repeated occurance. The smaller chambers of the 194 head do more to restrict breathing than is gained, and therefore both tlowe and myself are not going to endorse this modification as a way to be beneficial to the enthusiasts seeking to do this.

Beg to differ on that point. 1963 and later Chevy inline was base engine in some GMC models, just don't see many. If o.e., hood will never have been drilled for V6 emblems.

My 2cents is I dout the valves were unshrouded properly.The 194 I did OUT ET a big chamber head. The car went from a 9.27 to 9.16
This was on a 250. This same head flowed over 180cfm on the
exhaust with a 1.6 valve. Maybe?????? the 292 acts differently
with the 194 due to the Longger stroke?

The 250 dyno tests we are going to be conducting are going to be using the same heads for that as well, so we'll see if that shows any additional results to support that or not. Also, for many years, a lot of people for some reason or another, have the misconception that you get a magical or phenomenal increase in power with only a very tiny increase in compression, in this case, hardly 1 full point. So, its possible that this performance gain was or could be contributed to something you had absolutely nothing to do with at all. Unless the head swap was done at the track, the same day, under the same track and atmospheric conditions, its possible that those variables had more to do with the gains seen, than the head itself, so consider those possiblities as the reason. Irregardless, most people look to dyno results as being the absolute authority for debates such as this, because a dyno is a more controlled environment, and a track has too many variables to consider. But, we'll see how a 250 reacts with that same head on it.

It might be good to should show some pics of the chambers so we know how much & where it is being unshrouded.

It's hard to critique someones work w/no pics here on the bulletin board.

What size valves are used on the small chamber head,I forgot?

It just seems a little hard to swallow,, a small chamber head that flows the same as a large chamber head.

Do both heads flow roughly the same on the flow bench or were they even flow tested @ all for comparision? Had to ask,no flames please!

Thanks

MBHD

Hank,
these 2 heads in question are going to the flow bench next, for the same reason.
Both heads have 1.94/1.60 valves, same chamber clearances between intake valve and chamber side. Simular port work too. Tried to be very fair with everything.
Tom

Hank, I have very thick skin and nothing you or anyone can say to me is going to change my blood pressure, this data "is what it is", if others want to throw stones at it, its their lose, not mine. Its a free education for many, and they should take notes, instead of fall asleep in class. Both the small chamber head and large chamber head have 1.94" valves, and where unshrouded at the same time with the same tooling for each head, and both also had lumps. Why do you think that just because the chamber is smaller it flows better. At low valve lifts such as these seen on street type engines like this, the chamber still shrouds the valves too much, even after unshrouding. Thats why in the full boogie race engines like Cotton's and others I have experience with, we had to run valve lifts that were almost 1.000" inch of lift, so the valve would open up past the point where the chamber had no effect on the flow, almost like there was no valve in it at all. On these heads here, even at .600" valve lift, the valves are still way down inside the chambers suffocating in a small chamber head. Now keep in mind, we are talking a stock, untouched chamber on each head, other than the fact they were unshrouded with the same tooling, the same amount at the same time of the valve jobs. You can naturally take a drum roll and roll the chamber back on the smaller chamber heads to dramatically improve the shrouding it has, but you don't totally eliminate it, like a large chamber has to begin with, plus you are opening the cc's back up as well, and defeating the purpose of why you are putting the smaller chamber head on to start with. A flowbench wont tell you these things if you don't have the correct size orifice, or if the head isn't placed on the orifice in the correct orientation just as the head fits on a 6 cylinder block. The basis for all this dyno testing is to do just what it is doing, and that is to confirm beliefs or reveal misconceptions that have always been held by a lot of people. This is the very first time that anyone can actually see a direct correlation between what CFM and HP actually means for these heads as well. Unfortunately, its going to bust a lot of peoples bubble about what they have believed for a long time, and not just on this small chamber vs. large chamber debate either. We have found so many other discrepencies that have long been believed, that are just completely wrong we could write a book....oh yeah, we are. But seriously, this should be looked at as a free learning curve to those that didn't contribute to this project, and take this data, and use it to further advance their knowledgebase and efforts, because flowbench data by itself is completely worthless, unless you can show what it means. And a dyno will translate that into real data you use to mean something....and thats what we have done.

Thanks for the info!
Not trying to raise anyones blood pressure here,if by me asking questions you are offened,I appologise.

Me personnally ,I would never install a 1.94" intake valve in the small chamber head.

We found out quickly the cfm loss was too much. Chamber shrouding was too much,I I wanted compression,& opening up the chamber was not going to help my quest for high compression.

So we went w/a smaller size intake valve.

We were getting more flow useing a 1.85" valve over a 1.94"

As far as me thinking smaller chamber head flows more,,,not sure what you are referring to?

Actually just the opposite most times.

BBC small chamber bath tub heads are almost the worst flowing BBC head other than smog round port heads,not oval.

We had to open up my already large chamber head to get more CFM out of it.:a couple pics



As far as cylinder head flow & actual real time street/track differences & comparision,I have done many.

I have flow tested pretty decent 6 cyl cylinder heads & work absoultly horrible on the street or track.

It's not always about what flows the best to what will work the best on the street. Sometimes,they just do not go hand in hand
;-)

Keep up the good work!

MBHD

Hank, I probably wouldn't put that large of a valve in a street small chamber head either, but we wanted to perform many of the same mods to these heads, that someone that might not be as knowledgeable as others would do, to show also what doesn't work. You obviously know that, as I and Tom know, but you would be surprised how many other just dont get it. And, thats what this testing is about, to educate and help clear up a lot of these misconceptions that others do have, thats all.

O,,forgot,,any chance of posting up some pics here so the students don't fall asleep?

Pics are always educational & for the most part,brings some color into just a BB w/typing.

Kinda like typeing this,hey guys I just installed a larger compressor wheel on my stock turbocharger.

Or.hey guys,check this out ,I just finished installing a larger compressor wheel on my stock turbocharger.
BAMM!

I'm a bit sneaky that way & like a sleeper look.

Thanks

MBHD

That is why I questioned if they had been flowed tested.

I am pretty sure you are going to see the small chamber head does not flow that well & the reason being the vlave is too large or it needs more unshrouding.

Let us know how the two heads fare to eachother when you get a chance,,doing great!

MBHD

Hank, last week in another post when tlowe said the small chamber head was a waste of time to modify, based on the results we discovered on the dyno, you acted shocked and surprised that this could even be possible, now you are agreeing that the smaller chamber head doesn't flow as well with the big valves as the big chamber head does. All this info was revealed when we said it lost HP over the big chamber head....

Can someone show photos of stock 230/250/292 and 194 head combustion chambers in one post?

Great idea . I will get that done. Tom

Hi all!

Hank, so what kind of power difference should you expect from your compressor wheel mods, that is sneaky.

I think after I get it all dialed in,I am thinking about 40 HP maybe a bit more.

With the larger wheel I will be able to run more boost ,but for now my injectors are too small,I have a set of 36's ( stock is 30 )I will be installing.

Maybe then I can run 11's on pump gas. Truck is heavy 3600 lbs no driver.

My converter is too tight also,2100 stall. I need closer to 2600-2800 range.
It all just cost money & I have too many projects going on all @ the same time.
One of my other projects is a 1986 Yamaha Fazer 700 & me & my friend installed a FZR 1000 engine into it,bolts right in ;-)
That's sorta of a sleeper looking bike also.

Most of my vehicles I try for a sleeper/stock look,that's just the way I am,,,but whenevever I get the Camaro going,,it's not going to look much like a sleeper other than it has a 250 ci engine & that's not even going to look stock.

I made carbonfiber bumper brackets just trying to keep the weight down.

MBHD

I believe I read it in Leo's book that he or some of the other racing head porters concluded that 64cc chambers seamed to be the smallest chamber size to be the best at getting flow without doing some intensive chamber work like Hank has done. When I first got Leo's book and going through it I really didn't think much of it because most of the book covered highend HP being more in line with all out drag racing performance and not street performance, at the moment I am unable to locate my book to see if that is where I saw this information.
On another note: I have a guy that does my Harley heads and during his learning experince with porting he drilled a hole down through one of the valves and used a micro camera so he could watch what was happening with flow and what was happening in the chamber and cylinder. Before working on Harleys he was an engineer working on jet engine design and performance, needless to say he builds some nasty street Harley motors, he also now makes pretty much most of his own stuff, Cams, Cases, Heads for Harleys.