Build a better BOSS Engine

[pufferfish]

Wooops! Fixed ;D

 

[Brandon302]

Did you end up getting the better valve springs for the heads when you put your motor together?

 

[pufferfish]

nope, the heads came assembled with boss springs, which are good enough for the cobra jets, so they are good enough for me!

on a side note, I am going to get a proper tune from Revolution Automotive next Tuesday. Shaun at AED recommended them over a remote tune from him. also told them my situation and the desire to have a tune for the GT intake and the Boss. They are very excited about this as they have long speculated a GT intake will make better useable power than the Boss does, but never had a legit boss engine to try it out on. They may actually be more excited than me!

now, what do you all think it will put to the tires? closet to actual gets a slightly burned GT crankshaft!

performance mods at a glance:
100% stock boss long block (except cj pulse ring and billet oil pump gears)
granatelli cop's
stock iridium plugs at stock .052" gap
kooks 1-7/8" shorties
stock h and axle backs
gt500 mufflers
3.55 gears
spec clutch with aluminum flywheel
dynotech driveshaft

guess #1: with the gt intake and stock cats

guess #2: with the boss intake and stock cats

guess #3: with the winning intake and no cats

 

[steveespo]

#1 400 hp @ 6000 rpm, 395 lb ft Tq @ 4800 rpm
#2 428 hp @ 6750 rpm, 389 lb ft Tq @ 5252 rpm
#3 Boss intake no CATS 435 hp @ 6750 rpm, 395 lb ft Tq @ 5252 rpm

Boss intake will carry 420+ HP from peak to 7500 rpm
GT Intake will fall off from peak to being unusable above 7100 rpm
You didn't think I would think otherwise did you?
Steve

 

[pufferfish]

I expected nothing less from you Steve! I do like your very specific numbers with their rpms! NICE! The numbers don't sound too far off of what I would expect. I can tell you though, that with the gt intake and boss heads, it peaks above 6000 on the butt dyno. I also would expect the boss to peak above 7000. when i had the boss intake on my stock gt motor, i had it dyno'd at Carlisle and it was still slowly increasing to the 7500 redline. i also contend there is more to be gained by cat removal than 7hp. from what others have reported, its more in the 15 range.

another factor is the lightened flywheel and driveshaft. its going to lay down more power just from this. guy on svtperformance put 460 to the tires on a stock boss engine and MT82 with only a cai and tune by lightening the drivetrain with aluminum flywheel, ds, lightened and polished ring and pinion and lightweight wheels.

i won't be lightening my gears for longevity's sake, but the reduced friction from polishing is probably going to be my next mod. and at a $150 adder, polishing is an easy decision! the hard one is choosing to polish 3.55's or 3.73's? i really can't decide.

 

[Brandon302]

Do you really gain much from going from a 3.55 to 3.73 or vice versa?

 

[pufferfish]

without shoving all the math in this post, 5th gear with a 26 inch tall tire, setting a 7000 redline (as i would do with the GT intake) is 148mph with the 3.55's. I would have to spin to 7350 to match that mph with the 3.73's. this can make a big difference on track.

of course, the boss intake would take the rev limit to 7500, which puts me at 158mph with 3.55's or 151mph with 3.73's. 151mph should be plenty for most areas of the tracks, but do I want to run the bajeezus out of the motor or take it a bit easier for longevity?

so, I think the 3.55's if the gt intake wins, and 3.73's if the boss intake wins.

 

[steveespo]

Steve
My numbers are based on Dyno Jet with SAE Correction and smoothing 4 or 5. Raw SAE numbers will be 5-10 HP higher and the end of the trace will have a spike that distorts the numbers. My SAE corrected unsmoothed numbers were 443 HP, with SAE 5 smoothing the "real" numbers are 432 HP at 6950 with 422 or more right through to 7500.
I have full length American Racing Headers with 3" cat less X-Pipe and 85mm BBK throttle body.
Steve

 

[pufferfish]

Those are great numbers, but of course dyno jets do read high. I am surprised at the peak HP. Again, I peaked somewhere north of the 7500 cutoff.

 

[pufferfish]

one more day! I have decided to bring 2 of my track wheel/tires to swap on the rear before going on the rollers. since the track is where I care about the power, it makes sense to use them. why, you may ask? well, they weigh 13lbs (each) less than my streets and the tire diameter is smaller...both of which will effect the readings. the lighter weight should produce more power, but not sure which way it will go with shorter tires?

oh, and I found out they use a Dynojet, so it will likely be a higher than average number. but the big point of which intake is the winner, will still be accurately represented.

 

[steveespo]

Dyno Jets are the most common out there around here, what have you been using a Mustang Dyno?
Steve

 

[pufferfish]

I actually don't know what it was originally dyno'd on. it was a mobile unit. All my previous cars were dyno'd on Mustang dynos (load bearing), which are supposed to be more real world accurate than Dynojets.

 

[pufferfish]

Dyno tuning complete! Thank you Revolution Automotive! What a great group of guys! Adam spent all day maximizing the tune for BOTH the gt and boss intakes, so I can run either with absolute certainty, that it will be safe.

I will follow up with dyno graph and video tomorrow, but I couldn't keep the results to myself until then!

I didn't quite get the comparison I said I would do. After talking to them abut the cats, they assured me I could pass MD emissions without cats, so they were ditched before any pulls.

First, the bama tune with the gt intake for the baseline (didn't get a graph on this one): 426/403 good numbers, but the tune was too lean and was bumping the knock sensors. It may have been due to running without cats? Who knows?

GT intake tune took some time to smooth out, since it may have never been placed on top of a boss motor and certainly never at rev auto.

The boss was easier, since it was essentially a stock boss engine, so he only had to account for the kooks shorties. The only issue was above 7500 rpm in 5th gear, the dyno was maxing out in mph and effecting the readings. So, for the sake of the boss intake, a 4th gear pull for both intakes was done.

5th gear pull (1:1):
GT: 428hp at 6600rpm, 413tq at 4400rpm
BOSS: 426hp at 6600rpm, 388tq at 4600rpm

4th gear pull:
GT: 430hp at 6700rpm, 396tq at 4400rpm
BOSS: 441hp at 7500rpm, 377tq at 4700rpm

When the dyno was kept within its happy range, the boss shows its legs! It made about 430hp at 8200rpm! Very impressive indeed!

But of course, the max numbers don't tell the whole story. The boss intake was down on hp (15-30) and torque (10-20) until around 5800, where they were dead even until 6700, where the gt fell off and the boss leveled off until 8200. So, if I live my life between idle and 7000rpm, the GT intake is king. If I life life from 5800 to 8200, the BOSS is, well, the boss!

Taking into account that I will be running TT3, which has a HP to weight ratio rather than mod points, I could run either intake and be ok (based on 5th gear pulls as the official number). So, do I want to wind it out or keep the grunt?

The big surprise was the fact that the GT intake only dropped about 15 HP from 6500-7000, which is much different from GT engines with a GT intake, which drop by nearly 30hp at 7000! So, the heads and bigger exhaust cams do help extend the GT intake's range!

So, that's the facts...discuss! Or wait until tomorrow when you can see the graphs.

 

[Theviking]

The big surprise was the fact that the GT intake only dropped about 15 HP from 6500-7000, which is much different from GT engines with a GT intake, which drop by nearly 30hp at 7000! So, the heads and bigger exhaust cams do help extend the GT intake's range!

Curious, would the GT intake even make power to 8k or did you let out of it sooner?

 

[pufferfish]

Dyno was stopped at 7300 for the GT intake. It seemed to be a waste. Losing 15hp in 500rpm, may be good for a gt intake, but it still is not good. If the dyno continued, I believe it would have fallen off sharply.

 

[Brandon302]

Did you have the redline raised to 8200 or are you keeping it closer to 7500? I guess it all depends on which intake is used.

 

[pufferfish]

Good question! I know the redline is 8200 for the boss. Not sure if they set the gt intake tune that high?

 

[Brandon302]

I'd hope not since you stated the power starts dropping off close to 7k.

 

[pufferfish]

 

[steveespo]

Great numbers Steve. GT manifold really performed well.1000 rpm over run with the Boss Manifold is nice to have IMO. Your going to have to do back to back track days with each manifold and have telemetry data to see what gives the best performance.
Steve E