some interesting tests with the g54b
so i started punching around on the internet putting together data in my dynosim program to try and cobble together a accurate g54b engine i can use to baseline what some performance mods can do. i have found power numbers ranging from 105 to 145 on n/a motors. so i just tuned the motors to a more streetable tune and here are my results with various mods (about 13-15 afr and 5-10 degrees timing, where most people run)
stock: 122/159 @ 5000/3500
cat delete: 129/165 @ 5000/3500 (5 free hp)
muffler delete: 133/168 @ 5000/3500 (another free 5 hp)
long tube header no cats with muffler: 160/182 @ 5500/3500
HANG ON...
youre telling me a stock motor with a long tube is worth almost 40hp over stock??? yep! this is often case with alot of stock engines and smog engines with small port heads. it seems the extra flow of the long tube really helps expand power across the board!
my 3.8 chrysler i dynoed with stock manifolds and cats and mufflers on a single pipe just to see exactly how restrictive it is. it made 210 hp and 294 tq (lost 5 hp and gained about 50 tq, which makes sense with a torquey cam swap.) with long tubes and mufflers on dual exhaust it made 265 hp and 337 tq, which was a 55 hp and 43 tq gain.
so yes i do beleive this number is accurate, as mind blowing as it may seem.
lets go on...
long tube headers open exhaust: 170/189 @ 5500 / 2500-3500
the torque curve down low has been really helping this motor out.
now lets test carbs!
stock exhaust 32/36 weber: 125/161 @ 5000/2500 (thats 3 hp, but you lose the complicatedness of a mikuni along with that. all wins in my book!)
long tubes with mufflers and 32/36 carb: 165/183 @ 5500 / 3500-4000 (the torque curve is still very flat at low rpm's)
same setup open exhaust: 176/191 @ 6000/3500
now it seems the weber really helps airflow! now lets try the weber 38/38, individual carbs, and then a cam swap to see what else we can make!
38/38 long tubes with mufflers: 168/185 @ 5500-6000/3500 (a few hp and a few rpm's)
same setup open exhaust: 180/192 @ 6000/3500 (lots of hp and rpm)
quad 40mm motorcycle carbs, long tubes open exhaust: 180/198 @ 6000/3500-4000
now notice how with the 40mm motorcycle carbs and individual runners, it seems to want to be higher rpm. it actually made 10 less torque then the 32/36 with long tubes open exhaust @ 2000 rpm. maijor torque losses below 3000 rpm, which will hurt your mpg and towing.
now we will run a long tube induction with a shared plenum, and quad ford 300 carbs
now this engine went bonkers! 218/200 @ 6500/5000 AND IT KEPT TE LOW END POWER!!! 182 ft lb at 2000 rpm!
now we will do a common build. rv style cam, 38/38, long tube with open exhaust.
the cam is a schneider 260-70F
this setup makes: 184/195 @ 6000/3500
summary?
1: individual runners are a solid no unless you have a conquest or a charger
2: long runner shared plenum intakes are great!
3: the #1 mod is probably putting on a long tube header
4: webers are great all around carbs for some git up n go and that low rpm
5: you can make some really good power for very cheap (i have 2000 invested in my entire truck so far as the 4 cly is still in)
6: quad single barrels may be overkill until you build a motor
7: if you buy a cam make sure its rv style so torque is at a high
*note: all the numbers i mentioned are only estimates and may not be perfectly accurate. please do not take what i say as gospel, do your own research, and hop on a real dyno! this program is to only predict what an engine might do if you perform certain engine modifications!*
