badbryan87

Hello all,

I'm having trouble with not getting enough power out of my newly built 408 LS. It started it's life a L96 6.0 out of a 2015 3500 that I dropped off to be rebuilt at a engine shop. I asked them to work up three different quotes for builds. One for 550ish one for 650ish and one ~800hp supercharged option. The only requirements I set where it needed to run on 91 octane and not so much cam that it would die at idle as I wanted some streetability. After looking at the quotes I decided on the ~650hp build to give myself more room for swap costs. Well the other day was the big dyno day and well she topped out at 565hp@6400rpm much to my dissapointment. The builder said the cam he chose was what was holding it back and he gave me some suggestions for a different cam as well as how much it would cost to have done. However as I don't know a lot about engines I thought to seek outside opinions that and I'm kinda doubting if that would be enough to bring it up to expected power levels. I have kept all the info I was given on the build including parts and specs given so if I'm missing something you'd like to see out of the specs I list let me know.

408 (4in stroke 4.06 bore)
10.98:1 compression
ported 823 rec port heads w/ chamber vol of 69cc
LS3 intake w/ 90mm holley TB and 50# injectors
Pistons are Mahle 930223230 w/ a sligt dome and valve reliefs
current Camshaft Cam motion 03-01-0050 236/252 duration .621/.604 Lift 116LSA
suggeseted cam of 240intake no more than .650 lift and 112LSA Like the TSP BFD LS3 stroker cam
I don't know if it would fit(piston to valve clearance) but I was also looking at the TSP BFD LS7 cam

So Do you guys have any suggestions for what would be best to bring up the power? I know that the suggested cam specs would increase the power but 65-85hp gain out of 4-9 degrees of intake seems like a stretch. Any info or thoughts would help. It's going to end up in my 66 Chevelle which was built as a street strip bracket racer in the 80s. It will have a 4l80E and go out to a 3.73 rearend once those get finished. Thanks!

DualQuadDave

iTrader: (6)

I would leave the CM cam,add some 1.8 rockers and get the valve open some more. Shave the heads or go thinner head gaskets and bump compression some more. What valve springs are you running? Header size? I would run an efi Vic jr w/ a 4150 throttle body vs the plastic intake, but the plastic isn't horrible. What intake valves? Who did the port work?

1FastBrick

iTrader: (16)

So the current combo only Delivered 565 HP and was quoted to deliver 650 HP?

What parts were different from his 550 HP Quote to the 650HP Quote?

IMO to achieve 650 hp I think you are going into aftermarket head territory.

I think he missed the mark on the cam for sure but I think you may have other issues....

Who ported the heads?

Take a look at this build from Tony Mamo. https://ls1tech.com/forums/dynamomet...gas-build.html

Tony has built Several Stroker Motors and his full builds usually deliver what the customers are asking for. You can look at some of his other builds too to get an Idea what was used to achieve the numbers.

Old Buzzard

Before throwing money and parts at it, take a look at the tune that's on it.
Post up the dyno sheet.

ddnspider

iTrader: (26)

If you agreed on a power level and your goals and it was all understood then THEY should be fixing this to reach your goal. I would hope you haven't paid for all of it if it didn't hit the goal. Id start with that intake and look at your exhaust setup, but that cam needs work. Given your octane requirement I wouldn't add more compression either.

Y2K_Frenzy

Was the shop quoting motor horsepower or wheel? If they were talking about motor and you made 575 at the wheels then the 650 horse estimate isn’t too far off.
*Edit*
The engine was dynoed out of the car wasn’t it?

Che70velle

iTrader: (6)

If an engine builder misses a mark by almost 100 hp, and quoted you a price to hit that mark, then it’s 100% on him and the shop. Period. They messed up, not you. Now…it’s going to require likely more cam than you going to be comfortable with, with that intake setup. Also, there’s a very big difference between making 650hp at 6000 rpm vs making 650hp at 7500 rpm. You won’t like the street manners of the latter version at all, from a driveability standpoint, unless your willing to rev the car longer which means more mph…which means speeding tickets. 565 flywheel hp is going to translate to 465ish wheel hp, so there’s that as well. I’d start with a sit down meeting with the shop owner and your contract, and ask him for a clear path from him…ON PAPER… to get to the numbers he promised you initially. You’ve already paid for 650, now it’s up to them to get you there.

badbryan87

DualQuadDave - intake valves are melling 2.165 diamiter. exhaust are mellings 1.590 diamiter head gasket is Cosmetic 5751-051 .051 compressed thickness I plan on running 1 3/4" primary long tube headers from Holley. valve springs are PAC 1219-16 behive style. The engine shop did the port job on the headers

1FastBrick - When I sked him during the build he stated 630-650hp but probably closer to 630. the 550hp estimate was cleaning up the bores and putting forged pistons and connecting rods in(close to stock displacement) and a bigger than stock camshaft. Yeah I kinda thought more would be needed too and Tony's looks like a very strong engine. The shop did all the machince work including the porting.

Old Buzzard - I will upload what I have. I have the Terminator but I don't know how to hook it up to pull up the tune. it was done on a engine dyno with my ecm since the transmission isn't done yet

ddnspider - The engine has been paid for. This is the first time that I know of that they didn't reach what they stated. They've built motors and done work on lots of my friends stuff and even done work on two of my dad's motors. I plan on using 1 3/4" long tube headers like they did for the testing the only difference is these are made to fit my chevelle I will ad a section of extensions then add mufflers and dumps underneath to keep the exhaust simple. Yeah sadly 91 is the highest commonly available here I can occasionally find e85 and there's one place that sells 110 but thats it.

badbryan87

Yes the quote was engine hp and was dynoed on a engine stand as the tranny isn't done yet

badbryan87

There in lies the difficulty they did everything that they said that they would do to this engine build. The machining was all done and the parts they had planned on using were put in. The only deviation on their part was the cam shaft which was suggested by the cam makers and they decided to go with.

1FastBrick

iTrader: (16)

Was the porting CNC or just hand ported?

helicoil

iTrader: (104)

Looks like decent power for the combination of parts. Everything seems pretty conservative and pretty well matched. Dying at idle....I wouldn't be concerned with that unless your torque converter is VERY tight. There is definitely room on the camshaft choice before that would even be a thing. Any data on the heads after the work? What lifters are in it and what preload? If the shop says the combo is good for 650 and it is making 550, I would start with leaking it down to be sure it is sealed up!

01CamaroSSTx

iTrader: (3)

650 flwhp from a 408 with that cam, induction and worked over 823's all being choked off by 1-3/4 primaries? Not gonna happen.

B4CMaro

Interesting post.

I've built 2 408 ls motors now. This combination is very mild. I would expect around a MAX of 460-470 rwhp and 430ish rwtq from it. (Through an a4 locked) you will likely loose about 100 to the tire.

I have 2 examples:
408 with 11:1 compression, 236/245 112 .630. tsp 225 as casts. MSD manifold, headers and short travel lifters, and all the other usual things to go along with a build, made 470/430 wheel locked.

Same 408 shortblock, ls3 trickflows, ported fast mid runners, 246/266 111 .680 solid roller, 12:1 compression, header and the usual other things made 530 wheel unlocked.

You already paid for 650. He oversold and under delivered. He is either inexperienced or a con. If the story is straight.

00cls1camaross

iTrader: (10)

650 motor horsepower on a 408 with ported ls3 heads seems like a pipe dream to me. You going to have to get a lot bigger cam, aftermarket heads, and rev that thing to the moon.

badbryan87

1FastBrick - Hand ported heads but no flow numbers

helicoil - lifters are gm 12499225 I don't have preload numbers though. Rockers are upgraded stock with a btr trunion kit. No problems or leaks were detected by anyone during dyno sesh compression tested good

01CamaroSSTx - yeah I was kinda doubting just a new cam would fix everything. I cant find any larger primary swap headers for my car so it's what I am stuck with.

B4CMaro - interesting builds. Yeah I don't know either deffinitly make me question why i spent $4k more for 15hp

00cls1camaross - yeah that's what I seem to be getting or stick a supercharger on top and call it a day

spanks13

iTrader: (5)

Never should have been talking 650 hp ever that is the shop's fault. With a single plane intake AND the bigger cam you get to 630-650 on 91 octane.

I feel this combo is making what it is supposed to. Looks healthy on the dyno sheet.

I agree with Chevelle seat of the pants you'd probably enjoy this more than the engine making 650hp. For the 650hp version unless you have short gearing and a big stall torque converter it is going to be dog slow and drive like ***.

Power numbers you find around the net are typically very inflated. You won't have bragging rights with this dyno sheet, but it is likely a good healthy engine for your Chevelle.

SAPPER

iTrader: (10)

I agree with many others on here. I've designed a few engines, per se'. But getting 650 fwhp out of a 408 is easily attainable with all the right parts. None of which are cheap in the combo. Mainly the heads & work required. And especially with a hydraulic cam. If I had a customer wanting that from a NA 408, they would be paying me for a LLSR setup and Brodix heads. The cam would be a decent streetable cam with great reliability.
You're asking for hp numbers that coincide with more cubes like a 427 from a cam that mild.
So a few are all on the same page. where builder over sold his abilities.
But it seams you have a solid build that will hold that supercharger idea.....maybe.

jasons69chevelle

4.06 bores 4 inch stroke is a 414.
What lifters? Maybe giving power up there also if you’re not using a reduced travel style, or solid
Headers as mentioned already
What’s your elevation?

Tuskyz28

Ditch the LS3 heads