Rant: I hate engine builders!

[black1980fiveoh]

So mid June my engine blew at the track, I wasn't surprised as I was aware of an engine build error that would some day cause a big failure. Because of that, I have directly coordinated the engine build with a reputable machine shop rather than contract it out to a "pro" mechanic. I hate that I got suckered and believed all his BS!!

So the last engine builder, "expert" was suppose to build a 400 hp at the crank 302 that was going to be sprayed with a 150 shot of nitrous. After the build I came to discover that he put in hyperutectic pistons. So I knew the engine was a time bomb! My goal was a 13.5 on engine.

Since the disassemble, I've discovered that the pistons were also meant for high compression which cause me to scratch my head until I was informed my crank was not for a 302 but rather a 289. The machine shop estimated that the engine, at best was 8-1 compression but more likely 7-1 as the ring gaps were way too big. That explained the all the blow by. I was also informed, mismatched valves of different lengths were used. So is actually amazing that the car did an 11.8 in the 1/4 mile. The piston compression error reduced the wrong crank error.

This really explained why the can never really performed naturally aspirated as it should given all the trick flow heads and all the other go fast goodies. The engine lasted 20 000 km and ran 13.9 at best.

So now I have all the parts ready for a 400+ hp engine. Forged pistons with the correct ring gap, a 302 crank, and correct valves. I also now have a windage tray, main girtle, and 7 quart pan. On paper this 9 1/2 to 1 engine should be epic on nitrous and should hit or surpass my goal of 11.5 in the 1/4 mile.

If all goes well, the 81 cobra will be tearing up the track mid or late August.

[brianj]

I'm considering my next motor build, and stories like this are why I am going to only farm out the cylinder bore, and the crank machining. I am also using a factory Ford crank and rods. There are so many stories out there about bad machining, poor assembly work, and defective aftermarket parts (even big name, expensive brand name parts) that I am willing to loose the chance for a 331stroker in order to have some garauntee that I will have a reliable motor.

[erratic50]

Nonforged pistons and spray - what could go wrong? Lol. I'd say unbelievable but no it's not. I've heard of forged stock 302 pistons vanishing at machine shops just as quickly as they are pressed off the rods for oversized. Go figure.

In the same context what's moronic about the bad build with the 289 crank is that 289 cranks are worth a lot more money than a 302 crank to the right buyer!

One advantage of a 289 or 302 crank vs a 331 crank is physics. You can run more R's with a shorter stroke without using exotic rings and piston and rod and crank parts when the stroke is shorter. There are some formulas around for figuring out feet per second the rings are traveling.

Im also in the process of building a stock bottom end 302 with heads and cam targeting 400HP. Mine will be Typhoon EFI intake, Edelbrock heads, Comp cam, etc. Ultimately I'm looking at 11.5:1 compression via small chambers. I'm going to 47lb/hr EV6 injectors so I can run an E85 tune. The additional octane should be good for 12-15% more power via more octane and more liquid fuel further increasing cylinder pressure.

13.9 on motor is not terrible but the combo you had was definitely let down by bad parts. There are documented cases of HO302's running in the 12's on slicks with only suspension, tire, and gear changes. Or heck - look at the old Dominators!

Depending upon what your car weighs and what it 60's you should be a lot closer to 11's on motor than you think. If you can get your 60' where it needs to be anyway.

Good luck getting your new bullet cranking out the ET's you are after!

[erratic50]

Just looking at a few old article about foxbody mustangs vs performance - some were even running high 11's. Note there are stock E7 heads in play even albeit ported.

my notes say the formula is something like this

(Notchback 88 5.0HO 5 speed car with no AC or cruise, radio delete, etc)
rear seat removal
passenger bucket removal
28x9 slicks
4" skinnies
tubular upper and lower control arms
Rear swap biased to passenger rear
subframe connectors
high flow efi + 65MM TB + 70 MM MAF + cold air kit + k&N + removed silencer
or high flow intake and adequate carb
RAM air setup
underdrive pulley setup
short belt
electric fan
new plugs
Base timing advanced to 14+degrees
4 cyl rear springs
disconnect front swaybar
3.90 or 4.10 gears
2.95:1 1st gear stick trans
positive stop short throw shifter
adjustable clutch quadrant
light clutch and pressure plate
(Equal) shorty headers
exhaust dumps before cats
Comp cam 270HR or similar
RPM extender

Low 12's and high 11's *without* head, or intake swap just porting.

I don't think I'll ever match what some others have done, but they are out there.

Add a 150 shot to their results and you're bustin into the 10's probably.

heres a fun read https://www.stangnet.com/mustang-for...recipe.853108/

[deathbypsi]

Somebody is BS'ing you. If that motor had a 289 crank with 302 pistons and rods it would have the piston so far down in the hole it would barely make enough compression to run. If it has a 289 crank for sure it must have longer 289 length rods too which would mean you had a 289 and not a 302. Both motors have a 4" bore but the stroke and rod length is much different.

[erratic50]

289 crank and rods will make it to the top where it belongs.

[KWH]

If you tell the builder you are going to spray a lot, the correct thing to do is increase the ring gap, so I was told. That said, I have no idea how large yours were. I had a roller block with 289 crank and rods, very well prepared (for boost/spray) and balanced that would rev quite high. 1/4 mile raced and drove it on the street for 5-6 years before an exhaust valve gave up and destroyed a piston. Everything else survived though.
I couldn't imagine spraying a 150 shot without forged pistons.

[Haystack]

To be fair, there is more then one way to skin a cat. Roadkill just "built" a stock headed, stock cammed and stock exhaust headers with the flanges cut off from a 91 mustang. They added a $350 power stroke turbo and made 550hp and 600ftlbs on an engine dyno. They were pushing around 15psi which probably wouldn't live for a long time, but you could turn it down to 6 or 8 psi and reliably be pushing 350-400hp at wheels without ever dropping the oil pan.

[xctasy]

There is Bovine Scattology Somewhere.....

I grant you that if you have the base non HP 289 crank, then it'll operate....its resultant piston drop would be only 65 thou....if a 130 thou shorter stroke 289 crank would fit. One version does fit, but it doesn't operate as if your engine was born 50 oz, it would then have the wrong unbalance, and the other HP 289 won't as it has a different snout.

Even 300 Fords in Effie Trucks, and all 250 Mustang/ Maverick/ Torino/ Granada / Monarchs have a piston up to 123 thou down in the bore and still operate.

Ford designed the 1968-1981 Std Performance 302 crank to fit where a 289 non HP crank went. The rod difference is exactly 65 thou longer on the 289's (5.155 vs 5.090"), but piston is essentially the same.

With the 2.87" stroke 289 crank and 5.09" 302 rods, the piston will stop short an extra 65 thou down for sure.

[black1980fiveoh]

Im happy that things are getting fixed and i am overseeing the build. Im getting quite excited to get my cobra running again and start laying down some killer times at the track. While the builder made seriour errors, i think its funny that the errors almost cancelled each other. If i wasnt spraying nitrous, the engine and racing the engine would have probably lived quite a while. I am happy to know why it never made the right hp and im hoping the new engine will get better than 8 mpg.