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One more time BUILD THREAD I must be stupid

 
Old 01-28-2019, 01:50 PM
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Default One more time BUILD THREAD I must be stupid

So I guess im gonna try this one more time. I recently blew up my 418 LS3 build. Nothing but the heads are salvageable.

If anyone has any insight to help me not waste my money on the wrong parts I would greatly appreciate it.

My new motor will probably be as follows

Dart SHP block
4.125 bore 4.1 stroke.
cam motion solid roller
trick flow 255 heads.

my issues are :
cam selection
compression ratio
what is the limit of airflow of the trickflow heads.
what is the limit of the intake i have

based on my few runs i had before it blew. The other motors power was falling off sooner then i expected based on the big cam i had. was the cam just wrong? or are the heads maxed out?

Specs from the old engine

trick flow 255 heads with hollow intake valves
4.08 bore
4 inch stroke
2 inch headers
sheet metal intake and 102 tb
cam motion llsr
around 13.5 compression

here is the cam specs and dyno chart



​​​​​​

any help would be appreciated.
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Old 01-28-2019, 02:54 PM
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Someone like Darthv8r could definitely help you out with most of this.

But firstly, did you find the root cause of your first motor exploding? What happened? Knowing what caused the first try to fail, is probably our best learning experience.

Was it tuned at the Dyno? (Or just ran on the rollers for numbers?)
How was the AFR?
Was PTV checked?

Did the motor give any symptoms before its' demise?
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Old 01-28-2019, 03:29 PM
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Originally Posted by AndyTA View Post
Someone like Darthv8r could definitely help you out with most of this.

But firstly, did you find the root cause of your first motor exploding? What happened? Knowing what caused the first try to fail, is probably our best learning experience.

Was it tuned at the Dyno? (Or just ran on the rollers for numbers?)
How was the AFR?
Was PTV checked?

Did the motor give any symptoms before its' demise?

i dropped the heads off at the machine shop this morning and i showed him the carnage in the block. It appears the number one main bearing was starved for oil. which would starve the number one rod bearing. all other bearings in the motor look good.

to answer other questions.

it was dyno tuned
the ptv was check and there was plenty of room
afr's were perfect.

so im thinking there must have been something wrong with the block casting. When i bought the block it was used and the number one cylinder was scored which is why i had to bore it out to 4.08.

then last year i spun the number one rod bearing with no warning.

then last week i chunked the number one rod with no warning.

no oil pressure changes, no noises, nothing
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Old 01-28-2019, 05:48 PM
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Hopefully this one makes it to the track. Good parts list for sure.
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Old 01-28-2019, 05:52 PM
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When you had the machine work done, did they chamfer the oil holes?

I've seen some shops actually port the oil passages to the bearings to make sure it doesn't happen.

On your other thread... the priority main oiling setup on the Dart block kicks the LS2 blocks ***.
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Old 01-28-2019, 07:21 PM
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@AndyTA, thank you for the kind words

Short answer, on your heads carrying power into higher RPM, for the new, larger engine, tfs255 won't be enough. Even with someone like TEA touching them up, they are flowing around 375 at 700 lift. I'm basing this on you seem unhappy it did not carry out to 8000? Although, I do wonder how much of that was mechanical drag from the bearing dying. There are two cylinder heads that I think will meet your needs nicely. First is tony's 265 based off the tfs265. He's hitting 410 cfm with a 265 runner. Only one other head I'm aware of in that flow territory, and that's brodix BR7 273, which hits 415 cfm. Either way, those are both LS7 castings and ~40 cfm better flow from a very modest bump in port volume. Probably not what you wanted to hear, and I'm really sorry. But with both of these over 400 CFM, you should have a foundation for 800+ FWHP.

As to cam, when i was looking at a 454, I was at 12.5:1 and a 270/290 cam. I think that's about where you'll be on the cam specs. I think your current cam is enough cam for the 418. I think it will be small on a 440+. Depending on RPM, you may even end up in the 280/300 range. Would depend on planned compression, which of course is fuel-dependent. Cam that big should be OK, but idle like ****.

On intake, i wonder if you will need more throttle area than a 102 can provide. Your intake options may need to get more "exotic".

Something else to throw out there... consider porting the oil filter opening through the pan. to allow more flow through there.
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Old 01-28-2019, 08:14 PM
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Originally Posted by Darth_V8r View Post
@AndyTA, thank you for the kind words

Short answer, on your heads carrying power into higher RPM, for the new, larger engine, tfs255 won't be enough. Even with someone like TEA touching them up, they are flowing around 375 at 700 lift. I'm basing this on you seem unhappy it did not carry out to 8000? Although, I do wonder how much of that was mechanical drag from the bearing dying. There are two cylinder heads that I think will meet your needs nicely. First is tony's 265 based off the tfs265. He's hitting 410 cfm with a 265 runner. Only one other head I'm aware of in that flow territory, and that's brodix BR7 273, which hits 415 cfm. Either way, those are both LS7 castings and ~40 cfm better flow from a very modest bump in port volume. Probably not what you wanted to hear, and I'm really sorry. But with both of these over 400 CFM, you should have a foundation for 800+ FWHP.

As to cam, when i was looking at a 454, I was at 12.5:1 and a 270/290 cam. I think that's about where you'll be on the cam specs. I think your current cam is enough cam for the 418. I think it will be small on a 440+. Depending on RPM, you may even end up in the 280/300 range. Would depend on planned compression, which of course is fuel-dependent. Cam that big should be OK, but idle like ****.

On intake, i wonder if you will need more throttle area than a 102 can provide. Your intake options may need to get more "exotic".

Something else to throw out there... consider porting the oil filter opening through the pan. to allow more flow through there.
I agree with Darth here. Youíll need more head (air) to reach where you want to be, and itís easy to allow an intake to choke even the best flowing head down. For a max effort LS7, youíll need more than even a 108 can provide. Think dual throttle bodies here, unless you can get maybe a CID under your hood with a custom 4150 Tb? FWIW Tony has released a V 2.0 MMS 265 head with a bigger intake valve that flows even better than before. The Brodix head is very good also.
Ive spent some time thinking about your recent dyno mess, and until you mentioned today that your number one main was hurt, Iíve been scratching my head on that. You previously said all your main bearings were fine, which didnít make sense. The Dart block has priority main oiling, so youíll not have to worry about this anymore.
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Old 01-28-2019, 08:44 PM
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Old 01-29-2019, 11:19 AM
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I agree with both Darth & Chevelle re Tony's MMS 265 LS7 Heads, An alternative is Tony working your existing TFS LS3 Heads. He did a set for me that flowed 387 CFM @ .650". My Builder Dustin Lee Racing said they were capable of 800 HP at the crank shaft in the right build.

My 4.175" Bore 396" with 243/249 LLR made 690 Crank @ 7100-7300 Peak with 11.7:1 Comp and FAST LS3 Intake with Mid Length Runners. I would suggest the New Comp Hi-Ram Intake which is supposed to available shortly for both LS7 & 3 Heads.
That Intake will allow either type Head to reach its full potential with 440" & 8000 RPM.

I used a GM LSX Block for priority main Oiling which was a requirement for my build, along with a Dailey 3 Stage Dry Sump. There is horsepower (better ring seal etc, with a well planned Dry Sump Build) as well as longevity/reliability.

So just depends on horsepower goal and application up, to 800 horsepower I would have Tony work your Heads and put the savings into a better Intake. 820+ New Heads & Intake.

I am truly sorry for your Engine loss and wish you Good Luck with your current Build.
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Old 01-29-2019, 11:53 AM
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^^^^^ new heads not needed. Carb style intake for Real hp levels.
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Old 01-30-2019, 03:39 PM
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Thanks for the info. Got good news from machine shop. Heads are good! gonna replace the valves from number one cylinder and go through everything else.

Probably gonna run those heads until i can buy something else.

Trying to decide between strokes? 4.1 or 4.125

Also 4.125 bore or go bigger?

Regardless of what heads i end up using it pretty apparent the intake manifold is a problem.
I may get a holley high ram and modify it for a bigger throttle body? Or i may weld a larger plenum on my current manifold and use a bigger tb?
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Old 01-30-2019, 09:16 PM
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Who would you suggest specs my cam? last time cam motion spec'd it but i felt there was still more on the table.
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Old 01-30-2019, 09:23 PM
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Originally Posted by NAVYBLUE210 View Post
I agree with both Darth & Chevelle re Tony's MMS 265 LS7 Heads, An alternative is Tony working your existing TFS LS3 Heads. He did a set for me that flowed 387 CFM @ .650". My Builder Dustin Lee Racing said they were capable of 800 HP at the crank shaft in the right build.

My 4.175" Bore 396" with 243/249 LLR made 690 Crank @ 7100-7300 Peak with 11.7:1 Comp and FAST LS3 Intake with Mid Length Runners. I would suggest the New Comp Hi-Ram Intake which is supposed to available shortly for both LS7 & 3 Heads.
That Intake will allow either type Head to reach its full potential with 440" & 8000 RPM.

I used a GM LSX Block for priority main Oiling which was a requirement for my build, along with a Dailey 3 Stage Dry Sump. There is horsepower (better ring seal etc, with a well planned Dry Sump Build) as well as longevity/reliability.

So just depends on horsepower goal and application up, to 800 horsepower I would have Tony work your Heads and put the savings into a better Intake. 820+ New Heads & Intake.

I am truly sorry for your Engine loss and wish you Good Luck with your current Build.
When is the new comp intake available?

Last edited by topspeed1; 01-30-2019 at 09:32 PM.
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Old 01-31-2019, 12:44 AM
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You COULD NOT HAVE STATED YOUR TRUE INTENTIONS. Cams are designed to customers specifications.
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Old 01-31-2019, 01:03 AM
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Originally Posted by Smokey B View Post
You COULD NOT HAVE STATED YOUR TRUE INTENTIONS. Cams are designed to customers specifications.
^^^^^^^ This. I'd be willing to bet you changed a parameter after you spec'd the cam. OR left something out....
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Old 02-01-2019, 05:29 PM
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I think for now im gonna use my current heads to get it running. I really don't have the money to upgrade right now. Then im probably gonna get mamo 265s v2s

Darth is helping me with my cam. Thanks!

Next question i have is, Should I do 4.125 or bump it up to 4.155ish?

Probably gonna stick with 4.1 stroke maybe back it down to 4 inch?

Block is gonna take almost a month to get here, that sucks

but that give me a little more time to figure everything out.

Thanks again for the help.
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Old 02-01-2019, 05:40 PM
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4.185" bore and 4.125" stroke if NA. Block will handle it.

LS3 heads will perform much better on bigger bores. The LS7 will still out run it, but the bigger the bore, the better for LS3.

Look at this data for LS3 heads. The TFS 255 fixes some of it by rolling the valve over to 12 degree. But here's what a stock LS3 head shows:

4.090" chamber diameter

.107" between a 2.165" valve @ .400" lift and the chamber edge, that gives:

.062" clearance from the bore wall on a 4.000" bore

.077" clearance from the bore wall on a 4.030" bore

.095" clearance from the bore wall on a 4.065" bore

Most would say you need DOUBLE that. More bore helps a lot with the valve shrouding. A 4.185" bore gets the valve out .155" on a stock LS3... .200" is still ideal. The larger valve in the TFS head and the rolled valve angle sort of negate each other.

That'll help with power production.
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Old 02-01-2019, 10:33 PM
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Originally Posted by JakeFusion View Post
4.185" bore and 4.125" stroke if NA. Block will handle it.

LS3 heads will perform much better on bigger bores. The LS7 will still out run it, but the bigger the bore, the better for LS3.

Look at this data for LS3 heads. The TFS 255 fixes some of it by rolling the valve over to 12 degree. But here's what a stock LS3 head shows:

4.090" chamber diameter

.107" between a 2.165" valve @ .400" lift and the chamber edge, that gives:

.062" clearance from the bore wall on a 4.000" bore

.077" clearance from the bore wall on a 4.030" bore

.095" clearance from the bore wall on a 4.065" bore

Most would say you need DOUBLE that. More bore helps a lot with the valve shrouding. A 4.185" bore gets the valve out .155" on a stock LS3... .200" is still ideal. The larger valve in the TFS head and the rolled valve angle sort of negate each other.

That'll help with power production.
Youíre spot on here Jake, but Iíd add that the bigger the bore, the better for LS7 also. I moved the LS3 heads over .030Ē on the latest 6liter build I did. Started it today, and it runs excellent. Something to consider when shrouding is an issue.
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Old 02-01-2019, 10:57 PM
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No doubt!

However, OP has a good set of heads already, and if he's going to invest in the Dart block, the difference between a 427 and a 454 is nothing in price. Might as well use it to his advantage.
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Old 02-02-2019, 09:39 AM
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Originally Posted by JakeFusion View Post
No doubt!

However, OP has a good set of heads already, and if he's going to invest in the Dart block, the difference between a 427 and a 454 is nothing in price. Might as well use it to his advantage.
Agreed. For either his current heads, or Tonyís new V2.0 MMS 265ís, Iíd go 4.155Ē bore. Help the heads help you.
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