FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#1
|
||||
|
||||
Engine Dyno results questions
So my engine is finally done here is the combo……..
70 4 bolt main block, 461 , compression 10.2, 340 Cfm eheads,, port matched northwind intake, camshaft: 248 intake 254 exhaust 620 gross lift 112 lobe separation. I am also running a Holley terminator x with a 1300 cfm throttle body The engine was Dynoed with only a 750cfm carb as they didn’t have the setup to run efi on the Dyno and it made 551 hp and 555 torque at 6500 rpm When I bought my combo from butler the parts combo was put together with the goal of 650hp so I was about 100hp shy of that My questions is how close will I get to that with my 1300 cfm throttle body compared to the obviously to small 750 carb? The goal with the Dyno was only to break the engine in properly before I put it in the car which I accomplished and everything ran great! I just wanted to get your thoughts on how much HP and torque I lost with the engine being under carbed compared to what my goal is. Thanks as always |
#2
|
|||
|
|||
I do not think a 248 @ 050 cam would make 650 HP even with the best carb. You have plenty of head for more cam too.
Maybe I am wrong, cam just seems kind of small for your goal. I am shooting for a little past that 650HP number with a 461 but I have a lot more cam. |
#3
|
||||
|
||||
At 6500? Seems like something is off. That cam, especially with that carb, should have peaked way sooner.
|
The Following User Says Thank You to PunchT37 For This Useful Post: | ||
#4
|
||||
|
||||
I've built & dynoed a number of builds over the years with similar combos if not the same.
You can expect upper 500"s hp with proper CFM.
__________________
Carburetor building & modification services Servicing the Pontiac community over 20 years |
#5
|
||||
|
||||
Can you post up a dyno sheet please?
The fact that you on,y made 551 hp tells me that your flat out using only using some 275 cfm out of that 340 that the heads can flow. Your use of the 750 Carb took 25 to 30 hp off of what the motor could have made with something like a 950 cfm Carb. I also think that your pick of Intake Manifold is a bit of a restriction and needs some Plenum work and at least a 1/2" spacer. It would have been nice to know how much vacuum you where pulling below the Carb at the rpm of peak hp, I bet it was over 1.5 hg which is a indicator of a good size restriction. If you where looking for big power above 5800 rpm with the duration of that Cam it's not going to happen, this all being said I bet the motor as is will be a very nice cruiser and highway stormer! I would be very happy to just slap on your throttle body and enjoy the motor as is because your not hooking up on the street even the 550 hp your making now without sinking a very likely 4K more into the chassis and tires on the car.
__________________
I do stuff for reasons. |
The Following User Says Thank You to 25stevem For This Useful Post: | ||
#6
|
||||
|
||||
"I do not think a 248 @ 050 cam would make 650 HP even with the best carb."
+2 Not enough cam for 650hp, at least based on the 455 builds I've done here in the 600-650hp level. The last one I remember doing that made right at 650hp used CNC ported 330cfm E-heads, Victor intake, 2" spacer, HP 950 carb and 260/;260 @ .050" cam. Had a tad more compression too.........
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
The Following User Says Thank You to Cliff R For This Useful Post: | ||
#7
|
||||
|
||||
Ya dyno sheet. It would be interesting to know what the air/fuel was at 6500 with a 750 carb.
__________________
68 Firebird. IA2 block, 505 cu in, E-head, Solid roller 3650 weight. Reid TH400 4:11 gear. 29" slick. Best so far 10.12@133 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
#8
|
||||
|
||||
I will agree with the others that cam is not going to make it. Comparison my 500" IA with 330cfm E heads has a 268/272@0.050 on a 112 IC 108 and was about 650 non corrected 695 corrected with a 4150 850 carb.
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#9
|
|||
|
|||
More compression and valve lift would have helped. Intake work and spacer can be worth good power. Small carb will be hurting it as well.
Dialed in it has to be a 600 hp plus engine all day easy. I'm curious though was the dyno just used to do the initial break in and check for leaks etc...no real tuning was done?
__________________
466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 Last edited by ta man; 11-23-2022 at 10:26 AM. |
#10
|
|||
|
|||
engine dynos can be all over the place just like wheel dynos. the same engine will show different numbers on different dynos, lots of variables will determine the final numbers.
the numbers do seem low for that cam & heads. just as an example my 467 with stock 72cc round port E heads, 10:7, OF 236/242 cam with a ported HO intake & q-jet made ~520 hp with a fuel pump that was inadequite, & just under 580tq. a known strict dyno with no tuning to the engine, just bolted on the parts & did a few pulls while breaking it in & checking for leaks. seems like your engine with those specs should be making a lot more hp/tq, even with a 750 carb. im sure the EFI will help, but testing the car on the track will be the best way to show the ability of the car/engine. |
#11
|
||||
|
||||
Really cool build and I'm surprised they spun it that high with a 750.
__________________
Chris D 69 GTO Liberty Blue/dark blue 467, 850 Holley, T2, Edelbrock Dport 310cfm w Ram Air manifolds, HFT 245/251D .561/.594L, T400, 9" w 3.50s 3905lbs 11.59@ 114, 1.57/ 60' |
#12
|
||||
|
||||
Quote:
Isn't this comment an entire waste of time not knowing the details of the 750? |
The Following User Says Thank You to PAUL K For This Useful Post: | ||
#13
|
||||
|
||||
Thank you so much for all the feedback guys!
Yes, the purpose of the Dyno session was just to check for leaks and get the rings seated no tuning was done at all because of the carb. But good to hear when dialed in correctly I can hope to get over that 600 mark at least haha |
#14
|
||||
|
||||
Well it could be a waste of time I guess, but I was assuming that since the Op had a 1300 throttle body that was not used in that test that he would have also posted up if the 750 had seen rework to increase its cfm.
__________________
I do stuff for reasons. |
#15
|
|||
|
|||
Did they give you any AFR data? It had to be super lean pulling it that high.
|
#16
|
||||
|
||||
If the dyno had the type of Carb air hat that could measure cfm, then it would have been known in the blink of a eye if at any rpm point the Carb was trimming off needed cfm.
__________________
I do stuff for reasons. |
#17
|
||||
|
||||
Just fwiw, I made 620+hp with 243 duration. I'm sure 650hp can be made with 248 duration but things need to be right
|
The Following User Says Thank You to slowbird For This Useful Post: | ||
#18
|
||||
|
||||
Posting a dyno sheet would really help.
That said here is a WAG. Note even at a dyno correct = 1.0 it is not using 750 CFM. Stan Engine_Size_=_462.18350__-__Volumetric_Efficiency_=_0.83000 BSFC_=_0.46000__-__Air_/_Fuel_Ratio_=_13.0000__-__Blower_Pressure_=_.00 BSAC_=_5.9800__-__Barometric_Pressure_=_29.9200__-__Temperature_=_60.00 __________UnCorrected______Fuel _RPM______HP_____Torque___lbs/hr___SCFM _6500___552.62___446.51__254.203__721.54
__________________
Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
#19
|
||||
|
||||
Quote:
__________________
|
#20
|
||||
|
||||
Still you’ll be very happy with 585 hp, but yeah 650 be nice. Nice combo tho. Enjoy
__________________
|
Reply |
Thread Tools | |
Display Modes | |
|
|