SBC 383 500ft/lb torque build

[Scotthatch]

B Original thank you very much for your help. The old time engine designer gave me information and I sourced parts accordingly:

350 30 over

3.75 stroke

5.7 rod

12cc 1.425 compression height pistons

0 deck true parallel to crank axis

.039 to .041 gasket

EQ CC167ES2 heads 76cc 2.02 1.60

CompCams X4258HR 1.5 rockers

Edel RPM performer Air Gap

650 - 750 cfm carb

Pump 87 octane

600 - 800 idle

I have sourced a roller block. Calculations come to approximately 9 to 1 static? Maximum torque in 2500 to 3500. I don't know if you can use the 5252 rule for horsepower? Cam timing may need to be retarded 4 degrees. Not sure need to play with that. Again thanks for your help.

Here is what I came up with It appears that you have 9.07-1 compression with a 4.166 hole X .041 head gasket. I found that the best balance and bang for the buck was to shave the head about .020 and raise your compression to 9.3-1 to make this recipe.
Attached below the TorqueMaster spec sheet is a comp cams grind with Terry Walters part#. You can order it through him for the same price as a Jegs or Summit shelf grind. I looked at comp, erson, and and Comp lobe profile was the closest and least aggressive for longer spring life.

This grind is a 264 duration cam although the program specs a 263. The 263 is not a common lobe master profile so I think it is the better alternative. the compromise is 15.8" idle vacuum instead of 16.1" vacuum
This will have a small but noticeable idle rumbly quality but you will have a huge flat torque curve above 2000 and wont fall off much below that.

Now for heads will be fine although your's have a 167cc intake port volume. The alternative the program specs is a 150cc version. The trade off will be a modestly shorter torque curve at lower end of the RPM's and a few more horsepower at the peak and maybe a 100 rpm or so increase in the predicted peak. If your heads flow more CFM at lift, along with the higher lift of this lobe profile will make the Horsepower#'s modestly higher at peak.


383 torque motor speedtalk mtmvette.jpg

383 torque motor speedtalk mtmvett comp 1.jpg

383 torque motor speedtalk mtmvett comp 2.jpg

I like that camshaft in a lot of ways ... about the same port efficiency of 85% but with better valve exposure at peak piston velocity... the overlap point looks great to ... but it takes out 5 degrees at ex opening point ...I was not sure opening at 40 on the last cam was early enough

[groberts101]

lol.. I see no good deed goes unpunished. There are some major misconceptions here. Biggest one seems to be the thinking that simply shortening the cam timing, especially the seat timing numbers, will just automatically produce more and more torque at a lower rpms because there is more trapped charge, reductions in overlap and less cylinder pressure decay. I and just about everyone here wishes that were true! It reaches a plateau and just starts falling like a rock from there on. if it were true then we'd have never pushed diesel tech as hard as we have and everyone gas truck motor would make 600 lbs at 1,800 rpm.

Inertial and resonant are two entirely separate effects but can overlap and bunch up for improving overall results within a very narrow range. One can be achieved by reducing or increasing diameters/available cross sections and the other by increasing or reducing overall tract lengths. Obviously using both together is going to be more advantageous to the final result than just relying primarily on one over the other. The results, good or bad.. or even offsetting with a partial cancellation or negating affect.. are best used and leveraged in a cumulative manner.

Inertial tuning can be accomplished 2 ways. 1st is well known and involves higher piston speeds. That's a no-go here and part of the reason I rec'd higher compression ratio to slightly offset some of this design/parts shortcomings and help meet the intended goals. If you can't make the cylinder demand more air overall with higher piston speeds then the next go to is trying towards stronger pulse energy created with those higher compression ratios/smaller chambers. This also helps make a too big port(such as the typical cookie cutter 1.625" header primary that's likely to be used here) seem smaller to the engine and affects overall powerband more than some may realize. 2nd way is through reduction of port/header tube and/or collector choke sizing. If you have a lazy compression ratio and slower piston demand then it(inertial ramming effects) can be partially improved by increasing port velocities, thereby creating a faster moving fuel/air mass that hits the chamber harder and positively stacks against the back of the valve for use during the next induction cycle. It wont stack up nearly as much with the slower piston speed and increased length of time between induction cycles, but it is certainly not nothing either. Obviously by doing that you limit the engines peak airflow potential so it's a happy medium leading up to a choked airflow potential. Same goes for the exhaust side too. Smaller chamber will hit the pipe harder and make it seem smaller to the motor.

Resonance is quite obvious. Longer intake runners do not actually increase CFM capability unto their longer design.. they HURT CFM via increased surface area and velocity degradation over those longer lengths compared to shorter runners. They delay the returning waves to hopefully avoid dilution of reverse flowing combustion end gasses and signal interference during the next induction phase. Also gives the slower moving piston a fighting chance at stacking a little extra charge inertia within the longer tract to help out the atmospheres physical pressure limitations to dump more into the motor. This is why longer makes more low speed torque and shorter ones make greater peak horsepower at higher rpms. The sizes and lengths are all give and takes towards the desired results.

ALL... ICE have residual end gasses to deal with and some even pump it in to better fight emissions.. so no way around it unless you can do everything right and then some. The reason I keep mentioning VE all the time here is that is what's required in spades to reach 500 ft/lbs at such low rpm's on a sub-400" motor. Such an engine will/MUST be extremely efficient and have very high BMEP. If you want to be successful then you must use every trick in the book to get it.

Trying to laptop tune and datalog my boys truck today after some mod's and simply don't have the time to go through all the rest right now. Maybe I didn't articulate all the above thoughts the best way possible but is about all I can squeek out of my overloaded brain right now.

PS. 4.166 bore was mentioned above.. unless I missed something.. that must be a typo?

[GARY C]

That alone in conjunction with other well thought out and properly sized and lengthed components will be worth an easy 15+ ft/lbs in the range you're looking for here. It's not the biggest magic piece of the puzzle.. only the piece that brings the rest of a well designed puzzle together towards the desired result.

I feel that is the key to this whole build. I am jumping in as I am putting together an engine for my sisters truck right now. It will be a fairly simple 350 with parts laying around in the shop, so we are leaving a decent amount on the table. I understand this. If you really want to meet a target you have to be willing to do what it takes to meet it. If you want guidance helping maximize the parts you have then you have to be willing to let the chips fall where they may. That is where I am at with my current build. I would love to see 410 Ft/lb's out of this engine. I know if I used different parts and started from scratch then I could do better than that by a long shot. I look at what advice has been given and some has been great. Now the question is how much of your goal are you willing to sacrifice to stick with the parts you have? For my situation, I am willing to lower my expectation as I know the collection of parts I have just won't get me there. The current parts you have listed won't hit your goal. That does not mean that it won't be a great running truck.

The funny part for me is this, if the engine makes an honest 400 Ft/lb's, I could tell my sister that it makes 450. With the fact that she had so little before with the current engine, she would believe it.

Paul

There is probably far more people that have never truly experienced this kind of power in an actual street car than there are those that think they have.

I built a 468 BBC for my 77 Trans Am and based on parts was probably a solid 500 ft lbs, 550 would probably be generous but the only why to describe it was stupid fast and thats coming from someone that would test their drag car on the street with trans brake and primary stage of nitrous.

[Scotthatch]

Bigger cid and long stroke makes torque easy...

This is a 500 cid motor I did intake was too big so I did the port sear to flatten the curve and a smaller carb ..motor was not right in a lot of ways but ran well and did what it needed to do ... dyno was rear wheel and I live at 7000 ft up

[user-29956]

B Original thank you very much for your help. The old time engine designer gave me information and I sourced parts accordingly:

350 30 over

3.75 stroke

5.7 rod

12cc 1.425 compression height pistons

0 deck true parallel to crank axis

.039 to .041 gasket

EQ CC167ES2 heads 76cc 2.02 1.60

CompCams X4258HR 1.5 rockers

Edel RPM performer Air Gap

650 - 750 cfm carb

Pump 87 octane

600 - 800 idle

I have sourced a roller block. Calculations come to approximately 9 to 1 static? Maximum torque in 2500 to 3500. I don't know if you can use the 5252 rule for horsepower? Cam timing may need to be retarded 4 degrees. Not sure need to play with that. Again thanks for your help.

Here is what I came up with It appears that you have 9.07-1 compression with a 4.166 hole X .041 head gasket. I found that the best balance and bang for the buck was to shave the head about .020 and raise your compression to 9.3-1 to make this recipe.
Attached below the TorqueMaster spec sheet is a comp cams grind with Terry Walters part#. You can order it through him for the same price as a Jegs or Summit shelf grind. I looked at comp, erson, and and Comp lobe profile was the closest and least aggressive for longer spring life.

This grind is a 264 duration cam although the program specs a 263. The 263 is not a common lobe master profile so I think it is the better alternative. the compromise is 15.8" idle vacuum instead of 16.1" vacuum
This will have a small but noticeable idle rumbly quality but you will have a huge flat torque curve above 2000 and wont fall off much below that.

Now for heads will be fine although your's have a 167cc intake port volume. The alternative the program specs is a 150cc version. The trade off will be a modestly shorter torque curve at lower end of the RPM's and a few more horsepower at the peak and maybe a 100 rpm or so increase in the predicted peak. If your heads flow more CFM at lift, along with the higher lift of this lobe profile will make the Horsepower#'s modestly higher at peak.


383 torque motor speedtalk mtmvette.jpg

383 torque motor speedtalk mtmvett comp 1.jpg

383 torque motor speedtalk mtmvett comp 2.jpg

David definitely knows how to get it done!!! People need to stop and listen!

[Carnut1]

Vincent, glad you are back, losing pros left and right here.

[B Original]

PS. 4.166 bore was mentioned above.. unless I missed something.. that must be a typo?

The head gasket itself bore I.D. size lol most gaskets for a SBC are from 4.060-4.200 it means a variation of a couple 1/10 in compression ratio no biggie in most cases. 4.166 and 4.146 are common sizes I end up with.

[GARY C]

Vincent, glad you are back, losing pros left and right here.

[Carnut1]

Vincent, glad you are back, losing pros left and right here.

Gary, he may have an attitude but he knows his stuff and I appreciate input from pros.

[Rick360]

I recommend you cc the chambers and correct as necessary. The EQ combustion chamber can vary quiet abit. Compression is kinda critical when you want everything to work as predicted.

Reducing rotational friction can add Torque I prep the cylinders with a torque plate hone and a much finer wall finish that the 4oo stone leaves' along with a good 1.5mm ring set and piston (btw with the piston speed don't use a forged piston a good hyper coated piston if preferred) in most cases you can go from 25-30 lbs to 12-15 lbs thats good for at least 10-15 ft lbs

gvx (aka B Original), I thought you got booted off Speedtalk for pimpin DV's crap on here??? But I see your back at it.



Rick

[Carnut1]

I noticed GVX got booted, I haven't talked to him in a while. If you pay attention someone else is missing too.

[GARY C]

Vincent, glad you are back, losing pros left and right here.

Gary, he may have an attitude but he knows his stuff and I appreciate input from pros.

I guess I missed anything other than his backhanded comments toward DV or him hunting me down on the Political forum.

[Carnut1]

I stay off politics here, He is a character, reminds me a bit of Warp but he does give constructive comments... Sometimes.

[GARY C]

I stay off politics here, He is a character, reminds me a bit of Warp but he does give constructive comments... Sometimes.

Several have told me thats who they thought it was.

I don't venture down there much but he did, once!

[GARY C]

I recommend you cc the chambers and correct as necessary. The EQ combustion chamber can vary quiet abit. Compression is kinda critical when you want everything to work as predicted.

Reducing rotational friction can add Torque I prep the cylinders with a torque plate hone and a much finer wall finish that the 4oo stone leaves' along with a good 1.5mm ring set and piston (btw with the piston speed don't use a forged piston a good hyper coated piston if preferred) in most cases you can go from 25-30 lbs to 12-15 lbs thats good for at least 10-15 ft lbs

gvx (aka B Original), I thought you got booted off Speedtalk for pimpin DV's crap on here??? But I see your back at it.



Rick

I thought that was a guy named Mervin but how do you know if someone is banned?