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Building and Blueprinting a Road Race Motor (mini-build thread)

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The heads are the Boss 302 ones that already had the CNC program on them. Since I'm in a power/weight regulated class and didn't have infinite budget, I left that alone. I've not seen clear cut HP numbers for porting over boss head; there's flow gains for sure, but I hadn't personally been able to quantify a HP:dollar ratio for the work. Its certainly something I can explore down the road whenever its time to refresh this mill. I'm certainly happy to see anyone else's data; just none was available that satisfied my curiosity at the time.
Going back with what is known today, if anything I would consider the GT350 heads and a 5.2 block for what was spent and pick up the power/torque that way. I was initially shy on the valvetrain changes on GT350 and was a bit worried on the spray-bore blocks and the inability to service them beyond their initial bore/hone.
Oh crap!! :-( I so can't believe that I missed they were Boss heads. Thanks for the detail info, I just don't have the patience to document that much. When I was researching mine that was one of the things I looked at and why I went with the Gen2 heads. They are essentially Boss heads stock and then do benefit from porting. I'll dig up the flow numbers for you. I found 2 guys that worked the Boss heads and there was not much they could do maybe got a bit of low lift and then a few CFM (10) if I remember at .550.
And yes the spray bore oil burning is a no go for me. I thought about having a Gen 1 block sleeved to the 3.70 but it was too cost prohibitive at the time. I never though of the oil cross over on the heads. I've seen the cooling mod like that but never the oil setup until you.
Good Stuff!!
 

Mad Hatter

Gotta go Faster
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Santiago, Chile
When I was getting my gen1 heads ported the builder used my old Boss heads as the test bed. He also did my friends gen2 heads.. In the end after porting, both the Gen1 and Gen2 heads got to 330 cfm while the stock boss was around 290cfm. The stock gen1 was horrible (relatively speaking) at 278cfm. The Boss test heads actually got to 335cfm, but it was not worth the hordes of extra work to get the 5 cfm.

It was not expensive at all...... but took the guy about 7 months to do the worko_O. Glad we came to a fixed price at the start!!

Note: these cfm numbers were at 0.500 lift, Not much point going higher then that with the Gen1 LM intake cams, even the gen2 only goes to 0.512 I think. Love those tables with cfm numbers at 0.600.Not sure what cam would get you that.
 
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TMSBOSS

Spending my pension on car parts and track fees.
7,530
5,247
Exp. Type
HPDE
Exp. Level
10-20 Years
Illinois
There are three generations of the 5.0 coyote/roadrunner engine.
LMR has a good general explanation of the generations
The Boss/roadrunner as the big motor in gen 1. 444hp with better heads, intake and other improvement over stock 412hp engine.
 
When I was getting my gen1 heads ported the builder used my old Boss heads as the test bed. He also did my friends gen2 heads.. In the end after porting, both the Gen1 and Gen2 heads got to 330 cfm while the stock boss was around 290cfm. The stock gen1 was horrible (relatively speaking) at 278cfm. The Boss test heads actually got to 335cfm, but it was not worth the hordes of extra work to get the 5 cfmIt was not expensive at all...... but took the guy about 7 months to do the worko_O. Glad we came to a fixed price at the start!!
Note: these cfm numbers were at 0.500 lift, Not much point going higher then that with the Gen1 LM intake cams, even the gen2 only goes to 0.512 I think. Love those tables with cfm numbers at 0.600.Not sure what cam would get you that.
I like the L&M Intake only cams. But when you have ported heads like mine they actually flow well to .550 and .600 enough to justify the extra lift. So I had cams made to add the extra lift to utilize the flow. The boss heads are bad ass and that is what Ford took and used for the Gen 2 heads, so the Gen2 heads flow what the Boss did with all the work and got the springs, valves and Aluminum alloy along with the extra thickness around the valve seats. The angles of the intake and exhaust ports are much straighter as well. Basically they used the Boss project to proof the Gen2 Engine for production. Only thing different is basically the pistons, which are hyperutectic and not forged. :-(
 
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@captdistraction I was just there for a free education and to learn from somebody who has been there and done that. I enjoy learning from humble DIY people like yourself and others who share there knowledge with the Mustang community. The 50 car has been a R&D car for so many people on TMO something new members might not know. Your willingness to share your detail findings good and bad through the years has saved a lot of people including myself time and $. Im just trying to clone the 50 car more or less on my Boss build and not trying to reinvent the wheel. For those who haven't seen the 50 car, its even better in person! So for all of us who are trying to get our S197 Mustangs faster I thank you.
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
I like the L&M Intake only cams. But when you have ported heads like mine they actually flow well to .550 and .600 enough to justify the extra lift. So I had cams made to add the extra lift to utilize the flow. The boss heads are bad ass and that is what Ford took and used for the Gen 2 heads, so the Gen2 heads flow what the Boss did with all the work and got the springs, valves and Aluminum alloy along with the extra thickness around the valve seats. The angles of the intake and exhaust ports are much straighter as well. Basically they used the Boss project to proof the Gen2 Engine for production. Only thing different is basically the pistons, which are hyperutectic and not forged. :-(

Dont forget the valve sizes, the Gen2 picked up larger valves and more lift too match the Boss heads flow. Interestingly enough, Shaun mentioned that 330 cfm was more then the Cobrajet manifold could handle. Also that the LM cams dropped the lift but gained more power then the higher lift Boss cams or gen2 cams.

1612792591520.png
 
...Now one thing I'll get ridiculed for (and have been ridiculed for thus far, as regular as the sun rising every morning) is why didn't I just pursue a LS swap as the car gods at Vorshlag would recommend? I ran the numbers and considered it very carefully, more so than many would realize. I came up with $20k for a budget to do it end to end, and that's before all the scope creep and contingent items you don't realize until you're 75% into this. LS power is great, the torque is fantastic and its a lot less crazy work to make good reliable power; weights are fairly close all said and done but I decided that ultimately, spending half of that and keeping the recipe simple was the right move for me at this stage, and that if I wanted to explore LS power, I would instead chose to move to a platform that was built for that motor - IE corvette....

Despite being known for swapping, if your goal is sub 500hp, I'd stick with some variant of the Coyote rather than swapping to an LS. There is more support for the Coyote in an S197 or S550, and the engine faults are known and can be addressed. Where the LS works well is in the 600-900 naturally aspirated range. If that sort of power is needed, the LS become the budget winner.

And on the Corvette, those come with their own bundle of issues that get even worse with big power. They are hard to cage, don't have room for tall guys, have torque tube issues, and it's expensive to beef up the differential.
 

captdistraction

GrumpyRacer
1,954
1,698
Phoenix, Az
Despite being known for swapping, if your goal is sub 500hp, I'd stick with some variant of the Coyote rather than swapping to an LS. There is more support for the Coyote in an S197 or S550, and the engine faults are known and can be addressed. Where the LS works well is in the 600-900 naturally aspirated range. If that sort of power is needed, the LS become the budget winner.

And on the Corvette, those come with their own bundle of issues that get even worse with big power. They are hard to cage, don't have room for tall guys, have torque tube issues, and it's expensive to beef up the differential.

That's great insight. No platform when raced is free of trouble, and many from the outside looking in miss that. For ST2, 480rwhp/450average is the upper edge for power in a ponycar, and I'd argue that the fastest guys don't chase that number as much as chasing a lightweight car at the same ratios. I'm not the brightest as there's definitely some degree of desire to race this specific car and not just go find the most competitive platform for the class.

(in jest) the LS wouldn't need 8 pages of thread discussion though, maybe 3 in keeping in line with the simplicity of the platform. (lower end p1, assembly and upper p2, drysump p3)
 
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@captdistraction, I recently started building a Gen 1 5.0 for 100% track duty. My initial thoughts were a budget build with just ARP Fasteners, Manley Rods, Mahle Pistons, and Valve Springs. It didn't take long for the scope to creep. In my research I found this thread. I was curious if this engine is still serving you well and if there are any changes or adjustments you would suggest for track durability/reliability?
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
Having been through several performance builds, the best option for me is the most powerful, and!! cheapest!! Decent heads and a Gen 3 shortblock with minor options like the usual bolt-ons Cobrajet, LM intake cams headers etc leaves you pretty much at 600hp at the motor. No need for a LS swap... Last I checked, am at 507rwhp with 98 octane fuel.
 
741
1,075
TX
Having been through several performance builds, the best option for me is the most powerful, and!! cheapest!! Decent heads and a Gen 3 shortblock with minor options like the usual bolt-ons Cobrajet, LM intake cams headers etc leaves you pretty much at 600hp at the motor. No need for a LS swap... Last I checked, am at 507rwhp with 98 octane fuel.
I'm hoping my CPC, 5.2, dry sump motor lives long. If I only get another 40-50 hours out of it, I am going down this path and building multiples :)
 

captdistraction

GrumpyRacer
1,954
1,698
Phoenix, Az
@captdistraction, I recently started building a Gen 1 5.0 for 100% track duty. My initial thoughts were a budget build with just ARP Fasteners, Manley Rods, Mahle Pistons, and Valve Springs. It didn't take long for the scope to creep. In my research I found this thread. I was curious if this engine is still serving you well and if there are any changes or adjustments you would suggest for track durability/reliability?
I blew it up, but it was a oil pump issue, I think I aerated the pump and that took it out. Otherwise it gave 3 years of trouble free service. I wish I had done a real windage tray with crank scraper on it, or had gone dry sump and I'm sure it would still be in service.
 
When I was getting my gen1 heads ported the builder used my old Boss heads as the test bed. He also did my friends gen2 heads.. In the end after porting, both the Gen1 and Gen2 heads got to 330 cfm while the stock boss was around 290cfm. The stock gen1 was horrible (relatively speaking) at 278cfm. The Boss test heads actually got to 335cfm, but it was not worth the hordes of extra work to get the 5 cfm.

It was not expensive at all...... but took the guy about 7 months to do the worko_O. Glad we came to a fixed price at the start!!

Note: these cfm numbers were at 0.500 lift, Not much point going higher then that with the Gen1 LM intake cams, even the gen2 only goes to 0.512 I think. Love those tables with cfm numbers at 0.600.Not sure what cam would get you that.
Old thread wake up alert!.. i thought the Boss head guys didn't focus on CFM, they actually got lower flow numbers to increase avg power. I could be wrong.
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
Not too sure about that, Loved my OEM Boss engine as it was solid for years of track time... But as to power it was way lower then my present engine.. I could actually track the OEM boss in the rain. Now, just forget about it..... One toe on the accelerator and your spinning in every gear.

As to the stock oil system sucking air.... this video is from AED of a Gen3 getting into oil problems at +7000rpm. Scary.... Thats on a dyno... imagine at the track cornering with 1.4G!!

 

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