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Have you had the car tuned? Perhaps there's a lot more in it with a knowledgeable dyno tuner?
If you're worried about highway rpms, consider a 5 speed box? My TKO600 had more gear in first than the stock '79 4 speed, as well as the overdrive up top. And then you can add more rear gear if you need it?
If I was going to make a major change like an LS engine, I would just go 454 big block.
All the information in this thread has been appreciated, but frankly, the only thing I can gather from all of it is that the right way to build a 406 is to abandon my AFR 180 heads and my 1-5/8 inch headers. It makes a 383 maybe a better direction, although it will certainly be less of what I want than spending the money on a Dart SHP block, some good 200 plus heads and another header set.
I am just going to sit back and think for awhile before I do anything.
Maybe if someone would just buy my engine as a whole package, for enough money, I could think about starting over from scratch. When I built this engine, I took a lot of advice from this forum, and I think that as a 350, its pretty well built. Maybe should have picked a cam with more lift, but otherwise, I thought I was doing the right thing and spending the right money.
It just simply does not push me back in the seat like I think it should.
Just curious, have you listed your engine for sale on multiple platforms? You may be able to sell it as you're thinking. Then you can start from scratch and build something that will do what you want.
Another thought for large tq in small ci is forced induction! I would love to build a blown 400+ ci small block and maybe I will in the future. I do know that major tq down low can be had from a small engine. My Grand National is only 231ci V6 but makes well over 500 foot pounds,,,,talk about setting you in the seat....when it hooks
Just a thought, I don't think I saw you post about going FI in the thread earlier.
Last summer I posted a thread titled "Disappointed", on the engine below that I built in my 77:
- New GM ZZ4 factory hydraulic roller short block
- AFR 180cc Heads, 65cc Chamber 10:1 Compression (015 gasket)
- GM Factory Hydraulic Roller Lifter system
- Comp Cam Extreme Energy XR270 Roller Cam (218/224, .500 lift, 110 LSA)
- Comp Cam Ultra Pro Magnum Steel Roller Rockers
- Edelbrock RPM intake
- Quadrajet rebuilt by Lars (with the above engine specs)
- DUI Performance HEI Distributor (timed to 35 degrees)
- Stainless Works 1-5/8 inch long tube headers / 2-1/2 mandrel bent exhaust system
- Borg T-10 Rebuilt Original 4-speed transmission with 3:55 differential; New Spec Stage II Clutch
I drove the car about 4200 miles last year and while it produces great power and torque at 4000 plus RPM, truth is I am the type who likes big block torque, and I just feel let down by the engine at lower RPM's. The car is scary fast when you get it wound up. What I want is quick acceleration up to speeds I drive without running it to 5000 in every gear (Borg T-10 4-speed).
NOTE - I do NOT want to change this motor for a big block....simply too much of a change, weight and money.
So, I am thinking of building another motor to push the torque curve up at lower RPM, like a big block. but with stroked SBC. This is my plan:
- New Dart SHP 406 block
- Scat 3.75 crank with 6.0 inch rods and pistons for 10:1 compression and .040 quench
- Use my current AFR 180 heads....or go to 195 AFR heads??
- GM Factory Roller Setup
- Cam?? Something like hydraulic roller 230 to 240 @ 0.050, and maybe single pattern rather than dual pattern. I keep hearing the AFR heads do better with single pattern because of excellent exhaust flow. I would consider custom grind from Comps like Extreme Energy lobes on single pattern or Lunati??.
- Comp Cam Ultra Pro Magnum Steel Roller Rockers
- Edelbrock RPM intake
- Holley 750 Carb or stick with my Lars built Quadrajet
- DUI Performance HEI Distributor (timed to 35 degrees)
- Stainless Works 1-5/8 inch long tube headers / 2-1/2 mandrel bent exhaust system
- Borg T-10 Rebuilt Original 4-speed transmission with 3:55 differential; New Spec Stage II Clutch -
Many questions.
If I stick with my current AFR heads, I now have a short block to sell.....if I buy new 195 AFR heads....I could sell the engine complete....many of you said it was a great engine.....how much could I sell it for? Anyone interested?
My goal is to have a strong and flat torque curve starting down low at 2000 RPM . Hot Rod Impersonator 406 used Vortec heads, Impersonator II used AFR 180 heads. Both created the torque curve I want. Pushing up to 195 may start to take away from that just to have high RPM horsepower that I really don't care about. I am sure the car will go 75 mph very easily, and I am not racing anyone.
I also worry that a 1-5/8 inch headers is pushing small on a 406, and the AFR 195 heads will also be limited by it. Another reason to stay with my 180 heads. I do not want to buy another set of StainlessWorks headers at $1000.
The Hot Rod Impersonator series, and some of the builds in the Big Inch SBC book show that Vortec 170 and AFR 180 heads produce Big Block torque, and HP that is well within my needs.
Lastly, is my 355 rear end right for this engine? Would a 336 be better once I have the torque down low?
Thanks in advance for any input....Mako, BK Broiler, Lars, Gkull, Straub and 427...looking for your input.
Sorry I missed this one. If you looking for BBC torque then I would do the following:
4.125 x 3.75 x 5.7 Rod
Shoot for a compression
Reuse your 180cc heads (Keep in mind biggest factory head was 153cc)
Airgap intake with a 750HP Holley
1.6 Rockers
The cam I do for these heads, 560/540 233/235 on a 108
You would do better with a set of 1 3/4" headers
This combo will make more torque then HP as it will peak around 5800 rpm but the seat of pants feel will give you that BBC "sit in the seat, shut up and hold on"!
Sorry I missed this one. If you looking for BBC torque then I would do the following:
4.125 x 3.75 x 5.7 Rod
Shoot for a compression
Reuse your 180cc heads (Keep in mind biggest factory head was 153cc)
Airgap intake with a 750HP Holley
1.6 Rockers
The cam I do for these heads, 560/540 233/235 on a 108
You would do better with a set of 1 3/4" headers
This combo will make more torque then HP as it will peak around 5800 rpm but the seat of pants feel will give you that BBC "sit in the seat, shut up and hold on"!
Do the AFR 180's have enough intake cross-section to support a 5,800 rpm power peak on a 406? Even the AFR website says 'up to 6,000 rpm on a 383' with these heads.
Do the AFR 180's have enough intake cross-section to support a 5,800 rpm power peak on a 406? Even the AFR website says 'up to 6,000 rpm on a 383' with these heads.
When I called them about my 406 they said 195...everyone else 210+
Do the AFR 180's have enough intake cross-section to support a 5,800 rpm power peak on a 406? Even the AFR website says 'up to 6,000 rpm on a 383' with these heads.
At 5800 rpm you need 1.92 Sq/in. The 180 head has 1.92 sq/in. So the head will reach 100% capacity by 5800 rpm. I made a mistake in calculation and thought it needed 1.95 but it is in fact 1.92.
The reality for most is these engines are going to live 95% of their life between 2400 and 4400 rpm. Max rpm HP is not where the car lives. The OP put 4200 miles on the previous combination. So he is a driver. H also want BBC torque. We build torque with velocity. This head in the rpm range of 2200-4400 is going to have much better velocity then a larger cylinder head. This will give him that seat of pants Umph!!!!!!
Last edited by StraubTech; Apr 20, 2017 at 01:07 PM.
Reason: Made a math mistake...
The best part is the OP can use what he has to achieve his goals and doesn't have to spend an extra $1500. That will basically pay for his block. I'm all about achieving the goals with the best money spent.
sell what you have complete start fresh
You have a nice 350pkg as is
For how you desribe your wants I dont think a 383 will get it done.nice improvement but from 2-5k wanting what you want, may consider going bigger ci
At 5800 rpm you need 1.92 Sq/in. The 180 head has 1.92 sq/in. So the head will reach 100% capacity by 5800 rpm. I made a mistake in calculation and thought it needed 1.95 but it is in fact 1.92.
The reality for most is these engines are going to live 95% of their life between 2400 and 4400 rpm. Max rpm HP is not where the car lives. The OP put 4200 miles on the previous combination. So he is a driver. H also want BBC torque. We build torque with velocity. This head in the rpm range of 2200-4400 is going to have much better velocity then a larger cylinder head. This will give him that seat of pants Umph!!!!!!
From the Wallace Racing calculator:
Your RPM of 5800 and Bore of 4.125 and Stroke of 3.75 is a
Cross Sectional Area of 2.13 Square Inches.
Chris you are way more knowledgeable in this space than I am, but I didn't think you wanted to cylinder head choke point to be at the engine's HP peak. Wouldn't it nose over really hard? I'm sure this would be a great engine, but it just doesn't seem optimum if the OP is going to the trouble of an aftermarket block, etc.
Your RPM of 5800 and Bore of 4.125 and Stroke of 3.75 is a
Cross Sectional Area of 2.13 Square Inches.
Chris you are way more knowledgeable in this space than I am, but I didn't think you wanted to cylinder head choke point to be at the engine's HP peak. Wouldn't it nose over really hard? I'm sure this would be a great engine, but it just doesn't seem optimum if the OP is going to the trouble of an aftermarket block, etc.
MCSA of the Port. That is what is feeding this thing. This is the math we use when selecting a head for a given engine combination and rpm. We have already figured what we need to feed, we use piston speed for that. Based on the Demand that engine has we calculate out the smallest cross section of intake runner needed. This way we maintain the best average velocity in the port for the engine that we can.
Last edited by StraubTech; Apr 20, 2017 at 03:59 PM.
Reason: More information.
MCSA of the Port. That is what is feeding this thing. This is the math we use when selecting a head for a given engine combination and rpm. We have already figured what we need to feed, we use piston speed for that. Based on the Demand that engine has we calculate out the smallest cross section of intake runner needed. This way we maintain the best average velocity in the port for the engine that we can.
Why not send your 180 AFR heads back to AFR and have them upgraded then have a custom cam specd out and call it a day?
He may have to look up Tony, now doing is own thing mamomotorsports
Man thats a lot of o's
tpi421vette does some real strong big ci st/strip type motors here makes impressive power that are driveable and dont break. See him a lot in the C4 tech section Jims a good guy.
At 5800 rpm you need 1.92 Sq/in. The 180 head has 1.92 sq/in. So the head will reach 100% capacity by 5800 rpm. I made a mistake in calculation and thought it needed 1.95 but it is in fact 1.92.
The reality for most is these engines are going to live 95% of their life between 2400 and 4400 rpm. Max rpm HP is not where the car lives. The OP put 4200 miles on the previous combination. So he is a driver. H also want BBC torque. We build torque with velocity. This head in the rpm range of 2200-4400 is going to have much better velocity then a larger cylinder head. This will give him that seat of pants Umph!!!!!!
Thank you...this is exactly what I thought. But this thread raised so many doubts, I was at a loss on what to do other than spend a bunch more cash. Every book out there, all the reading, advice from certain posters I have come to believe in, ALL pointed to my interpretation and to what you have validated. The bigger is better ALWAYS comes up in these threads, and it seems easy to come to that thought....but there are some, like you that seem to disagree. Its about staying focused on what RPM range a person operate in....outside of that is useless.
You are being questioned now about your cross section calculation, so I assume you are not changing your position?? Please respond to that.
I am not taking any sides on this....I need to know what I am going to end up with, and I set those parameters on the first post. Seems to me the BEST way to make the decision is see a torque per RPM graph for each of the suggested combos. Put them all on one chart. The Camquest Online dyno charts is what I used to select the cam I have. Unless I am wrong, if I have a high torque number at 2000 an it runs flat or slightly rising to 6000 RPM.....then its easy to pick. Which combo makes this happen...that is the bottom line.
As I said, could care less what happens at 5500 and above.
Last edited by Shovels and Vettes; Apr 20, 2017 at 06:07 PM.
Thank you...this is exactly what I thought. But this thread raised so many doubts, I was at a loss on what to do other than spend a bunch more cash. Every book out there, all the reading, advice from certain posters I have come to believe in, ALL pointed to my interpretation and to what you have validated. The bigger is better ALWAYS comes up in these threads, and it seems easy to come to that thought....but there are some, like you that seem to disagree. Its about staying focused on what RPM range a person operate in....outside of that is useless.
You are being questioned now about your cross section calculation, so I assume you are not changing your position?? Please respond to that.
I am not taking any sides on this....I need to know what I am going to end up with, and I set those parameters on the first post. Seems to me the BEST way to make the decision is see a torque per RPM graph for each of the suggested combos. Put them all on one chart. The Camquest Online dyno charts is what I used to select the cam I have. Unless I am wrong, if I have a high torque number at 2000 an it runs flat or slightly rising to 6000 RPM.....then its easy to pick. Which combo makes this happen...that is the bottom line.
As I said, could care less what happens at 5500 and above.
We base everything off of math. Math does not lie....2 + 2 =4. We use math for Carb sizing, Intake Sizing, Head Sizing, and Cam sizing. I am fortunate we build a couple to 3 engines a year. These combinations back up the math...on the dyno and at the track. My engine builder customers that get head packages and cam packages back up the math on their dyno's and customers applications. I'm one of the few you will call that may tell you that your camshaft is too big.
Yesterday a guy called with a SBC 4.155 x 3.625 x 6" rod combo. Set of ported 230cc heads at 14.8 to 1 static. Camshaft was .720/.706 276/280 .050" on a 110. It made 660HP on the dyno at 7200 rpm. He was told by several he needed a bigger camshaft. I told him yesterday he needed a smaller camshaft. I told him based on the camshaft he has no cylinder pressure. I bet him it wouldn't pump 180#'s. I told him the goal is to squeeze the air and fuel as much as we can to get what we want...power. This thing should pump around 240# and based on 332CFM @ .700" lift make around 730HP.
Well he called yesterday, it pumps 160#'s. He ordered a camshaft.
On the math. We use the pinch in each head, the smallest area of the runner, to calculate. Wallace's even references for more accurate math use Pipe Max. I'll stand by what we use for math as we can back it up at the track.
