I am in the process of building a 372 from a Dart block i bought. Decided it will be cheaper to just build a new one rather then have the old one rebuilt. (especally because my old block is 2 bolt main)

Anyway i am looking for around 420-450 at the crank. Heads are Brodix ik180 with 64cc chambers and big valves. 9.98:1 compression. Intake is probably going to be MPFI. 2500 stall tc and 3.55 rear end.

Anyway i called lunati and they recommended 233/241 at .050, .504/.525
on the lift, and it is on a 110 LSA with a 106 intake centerline.

Does anyone have desktop dyno or something?

 

Are you de-stroking a 400ci block ?

 

no sorry for the confusion it is not a 377.

Its a 350 sbc 4.125” Bore x 3.480” Stroke so the actual cubic inches is 372.

 

If you leave off the 350 SBC your numbers might add up

 

Its the dart 372 SHP short block.

 

Anyway i called lunati and they recommended 233/241 at .050, .504/.525
on the lift, and it is on a 110 LSA with a 106 intake centerline.

Does anyone have desktop dyno or something?

Get a program print out not the phone tech recommendation.

Once u have the engine built then have your favorite cam company run the numbers through their cam program - most will run it for free if u buy their cam. The hard part is getting your volume/compression numbers nailed and the best way (really the only way) is to measure the volumes yourself with the engine on the stand and heads are off.
Asking for a cam choice here on the faceless internet is like asking a used car salesman for a good deal.

cardo0

 

Are you looking for a hyd roller, solid roller or flat tappet stuff? Specs will be a lot different.

I did a 400" Dart SHP shortblock with Dart 200 cc heads. Used a solid roller 248/248 on a 109 LSA cam with .614/.576 lift. We made 555HP with a single plane intake.

You could have used larger heads for sure. Keeping it down to 425 HP will be the trick.

JIM

 

A .030" over-bored 400ci with a 350ci crank is a 377ci, what you have is a new unbored 400ci with the smaller throw 350ci crank in it making it a 372ci. Correct me if I am wrong ??

I understand why they used to build 377ci's at the drag strip for high RPM passes but my 427ci with the same block ( size wise, different manufactuer) as yours would be a much better choice as it will rev to 7500RPM, I have a video of it on a chassis dyno at 7000RPM.

The point I am trying to make is; if you haven't already got the short block I would consider a bigger crank, nothing beats free cubic inches especially when you consider it won't cost you any more.

If you already have the short and heads let us know, at this point I at least don't know but would be better suited to help you if I knew you already had the parts. Also what the intended use for this motor helps,
like are you wanting to take it to the track often or is it just a tool around town build or 50/50, and I mean 50% of the time it's at the track which is quite a bit

 

I already have the shortblock and the heads. I would say 70 30 street strip. I live right near 131 dragway so i end up going a lot. I also do a bunch of Autocross. The cam they recommended was a hyd flat tappet.

 

IS that because of budget restraints ? Roller cams are the way to go but they can start to get expensive

 

partially budget also its what i have always used. Is it really worth going roller?

 

I read up on the Dart 372. You didn't say if you bought the forged internal parts options. The 372 being a short stroke was made to do rpm with the help of a roller cam to make HP. Your low 400 hp can be made with milder H-flat cams. the 231/238 should work.

I would not use Brodix ik180 It's bigger brother ik200 is a wiser choice. Actually 210 -215 cc work very well in sub 400 ci motors.

Personally I would not build such a small ci motor when the 400 dart kit was probably the same cost. the block was made to clear the 3.750 stroker cranks

 

Tried RSA's Engine Pro...
Results varied a lot depending on carburetor vs MPFI, and on manifold style - independent runner or common plenum - with results from 304 to 409 hp.

 

August 2008 Hot Rod Mag. took a test mule 355 ci and tested two heads the GM vortec and the AFR 195 cc eliminator and 6 different cams. They used the Weiand Stleal dual plane for both heads.

One the the cams was the exact specs of your lunati.

The motor with low flowing heads produced 389HP@5600 and 433HP@5900 with the superior AFR heads

The results would be about the same with your 372 ci. HP does not go up much with additional cubic inches, But TQ does. The article also used two larger cams. A larger H-flat that had poor lower end performance and only marginally high on top. The larger H-roller cam was up about 30 hp throughout the rpm range with more vacuum

 

What are your goals for the car? Are you looking at a drag race, road race, street cruiser, etc? That will help in the cam selection. Do you have the flow numbers on the heads?

 

Who sponsored the test? I am way too leery of magazine articles....they have one main intention "advertisement". It costs money to be in the mags...so someone is getting what they paid for in having their brand names in the ads, or in this case, the write-up.

Too many horror stories of dyno operators asked to fudge numbers or change outcome to meet the advertisers desires or intentions.

 

You are right! AFR probably paid for the rag to tout how great their just released AFR 195 Eliminator heads were compared to a modest flowing Vortec. So lets even say that the figures were mildly inflated. So what? You can mathematically prove HP "Potential" with a set of given head flow CFM numbers.


At my work when we dyno engines the owner gets the print out. No way to fudge those numbers. We actually don't even tune for the biggest peak numbers. We tune for the highest average with the full exhaust system from the car or something very similar because it would then be ready to go after installation compared to a dyno run and tune on uncapped headers to get big numbers.

 

That's the meat and potatoes right there.....who cares about one high rev...you want that all-time-performance under the "go pedal". Nice work.

I too think the OP should go roller to get the best out of their package deal.

 

Couple of things, I was always a bit skeptical of AFR's numbers too, I mean more CFM more money that's all it boils down to. I got my AFR227's flowed and they were right on the money so I am a believer now.

Second on dyno testing, when I got my 406ci dyno tested/ semi-tuned it made 550HP. When I put it back in my Vette I was looking for ( and I am not kidding here either ) a hole in the gas tank or leaking fuel line the mileage was so bad. I took the carb apart and the jets were huge, can't remember the exact size but they were for full throttle peak HP numbers which of course I wanted but to drive it around like that was not feasible.

So as gkull says you want a high average power range not peak power which you will find on all the test done in the rags on the news stand.

I am not picking on anyone here but I know for a fact when you see the huge chassis dyno numbers coming out of the S/C - T/C newer C5 and C6's they put the boost up way to high to be driven normally and even when the put the lower boost pulley on that they are going to use they have to use some type of detonation retardant usually put in the wiper bottle.

I asked the LS shop owner about it and said I was right, they put the highest boost they can to it so the owner can put that in his sig then they put a reasonable pulley on it so they can actually drive it around.

 

And since I am in the mood this is to the OP. In my own personal opinion there is NFW I would ever put a smaller crank in a performance block that has already been clearanced for a stroker crank. You have free HP at your fingertips and you want built something that will make less than my warmed over 355ci L48 did 10 years ago.

Please don't take offence but if there is any way you can swing putting ( in my mind of course ) the correct parts on that motor I would be doing it in an instant. You have an easy 500HP at your disposal which you could do even with the 372 and be perfectly "streetable" as in you could drive it around like a normal car but have plenty of power on tap.

Building a motor with Dart's new SHP block and looking for 400 and change HP I just can't understand it. You've got plenty of knowledge on how to do this with help from here on the forum. As it sits you are looking at 6 grand right now just for the block and rotator and heads for a 400hp motor, when it wouldn't cost much more for another 100hp/tq