434 sbc. Power loss from running a nitrous cam?

[riv187]

I bought a street racer monte carlo. I'm trying to make it a low 6 second in 1/8th bracket car. I will not use the nitrous the kit. I was disappointed at my first test at track,,we're sea level here in Florida. 7.01 98.6mph, 11.00 at 120mph 1/4,had to leave above idle off ft brake. The trans solenoid wasn't working when I went to stage,,. The car is about 3200 me in it. I really thought she would go 105-110mph without the nos.
I just started dissecting what I bought and found a low fuel level both ends of holley,, lashes from .026-.035",,,timing at 30*(apparently for the nitrous),,,and a Howards 111113-12s big bottle nitrous roller cam. 263/273 .682/.688 with 1.6 rockers and 112 lobe separation ground 4 degrees advanced.
Is the cam holding the engine back since I'm not on NOS ??? How much???


Brian

more specs I know..

434 with ross flat tops, tall single plane Pro comp intake and 2" spacer along with the 300 nitrous plate. 835cfm pro systems carb, 110 gas, Pro topline 235,64cc chambers,2.08/1.6. unported heads, 4.56 gears and spool. PG with 5000 convertor and trans brake.

[rebelrouser]

Just from my experience with a few friends cars, yes a big nitrous cam will knock one in the head, if you don't use nitrous. A nitrous cam bleeds off cylinder pressure to keep from burning pistons. A buddy bought an outlaw 10.5 nova, the previous owner had it running in the 8's my buddy was kind of scared to cut it loose, and ran it with no nitrous the first time, low 11's is what it ran. Hooked up the nitrous and it went a 9.20

[cgarb]

Something is not right...I got a 355 in a 3250lb car that will eat that up for lunch and it's nothing high dollar at all. What's the 60ft times? It seems to be down on mph...I would be looking for maybe some valve train issues like broken/weak springs.

[riv187]

Something is not right...I got a 355 in a 3250lb car that will eat that up for lunch and it's nothing high dollar at all. What's the 60ft times? It seems to be down on mph...I would be looking for maybe some valve train issues like broken/weak springs.

I agree it seemed like a dog for my expectations and a 434.. 1.55 60 leaving at 1800 rpm footbrake,,,as I wrote the transbrake acted up when I tested it before staging...so I just had to old school it. It did hook well and I didn't feel any spin. The chip in 2 step he had was 4400 ,,if I get the solenoid fixed.

[riv187]

Just from my experience with a few friends cars, yes a big nitrous cam will knock one in the head, if you don't use nitrous. A nitrous cam bleeds off cylinder pressure to keep from burning pistons. A buddy bought an outlaw 10.5 nova, the previous owner had it running in the 8's my buddy was kind of scared to cut it loose, and ran it with no nitrous the first time, low 11's is what it ran. Hooked up the nitrous and it went a 9.20

I ran a compression test on a couple cylinders I could get gauge too. It was 202 lbs and 207lbs.

I want to pull headers tomorrow and run a leak down on each cylinder...maybe higher leak though if he gapped rings for nitrous.
Not sure,,,but Vizard book has the 434 with 4" stroke at 104 LSA for race roller cam..made me think the 112 in this howard cam is no good.

[riv187]

Forgot to add,,,headers are 1 3/4" long tube with 3 1/2" collector. I think they are smallish for this combo,,,but not sure if it's the biggest problem choking it

[lefty o]

Just from my experience with a few friends cars, yes a big nitrous cam will knock one in the head, if you don't use nitrous. A nitrous cam bleeds off cylinder pressure to keep from burning pistons. A buddy bought an outlaw 10.5 nova, the previous owner had it running in the 8's my buddy was kind of scared to cut it loose, and ran it with no nitrous the first time, low 11's is what it ran. Hooked up the nitrous and it went a 9.20

I ran a compression test on a couple cylinders I could get gauge too. It was 202 lbs and 207lbs.

I want to pull headers tomorrow and run a leak down on each cylinder...maybe higher leak though if he gapped rings for nitrous.
Not sure,,,but Vizard book has the 434 with 4" stroke at 104 LSA for race roller cam..made me think the 112 in this howard cam is no good.

112 is certainly less than ideal.

[Geoff2]

200+ psi on a compression test sounds very high for that big cam.

[Outlaw383]

Yes the NOS cam and a NOS tune can kill the
ET/mph running it NA. Years ago I ran an S10 with 383 AFR210 heads and a small roller cam 252/256 @ .050 with a .630 lift.
With a normal tune up NA the truck went 6.42
Off the trailer. With just the tune up for running NOS done to that motor it went to 6.80s NA but with a 175 shot it went 5.98
The Nos cam will definitely slow you down
If the timing is set for the nos it's going to slow you down also be sure to check the heat range of the plugs you have, if you're trying to run NA it may have too cold of a plug in it.
Leaving on the ft brake at 1800 rpm definitely
Killed a bunch of your E.T. also. All of those things added together I believe is the reason for the 7.01

[riv187]

I appreciate the responses. On pulling the plugs, I found 3 wet. It didn't sound like it running, but they where rich. My initial track testing was cut short when I was trying to advance timing after the 1st full pass...old eyes in the dark trying see little flashing lines..and the starter failed after a cool down. Next day I fixed starter and fired t up and pulled plugs shortly after..It had a NGK 8 heat racing plug,,the tip recessed- not projected. This is a flat top motor so I was on fence to order new projected tip or stay same. My thought was he had the recessed plugs because nitrous?

[1980RS]

I bought a street racer monte carlo. I'm trying to make it a low 6 second in 1/8th bracket car. I will not use the nitrous the kit. I was disappointed at my first test at track,,we're sea level here in Florida. 7.01 98.6mph, 11.00 at 120mph 1/4,had to leave above idle off ft brake. The trans solenoid wasn't working when I went to stage,,. The car is about 3200 me in it. I really thought she would go 105-110mph without the nos.
I just started dissecting what I bought and found a low fuel level both ends of holley,, lashes from .026-.035",,,timing at 30*(apparently for the nitrous),,,and a Howards 111113-12s big bottle nitrous roller cam. 263/273 .682/.688 with 1.6 rockers and 112 lobe separation ground 4 degrees advanced.
Is the cam holding the engine back since I'm not on NOS ??? How much???


Brian

more specs I know..

434 with ross flat tops, tall single plane Pro comp intake and 2" spacer along with the 300 nitrous plate. 835cfm pro systems carb, 110 gas, Pro topline 235,64cc chambers,2.08/1.6. unported heads, 4.56 gears and spool. PG with 5000 convertor and trans brake.

First off welcome to the site. Here is what I ran last year that went 6.80's in the 1/8 mile and 10.90's in the 1/4 mile. My car is also a little over 3200 with a flat top 406, Mild ported Vortec 062's, Eddy SV ported, Elgin 1165P hyd cam and stock rockers, 1 5/8" cheapo headers and I was stunned what it ran that night. Drop the duration down and get a cam on a 106° LCA as it will help out the bottom end with your 434, look for a Holley 300-25 Strip Dominator intake as those a pretty good over the intake you have. Your car should be running 6.50's IMO but as I have found out it's all about getting the combination right with the right parts. If you were to change nothing else and went to a turbo350/400 I bet the car would ET better just the way it is.

[steve cowan]

I bought a street racer monte carlo. I'm trying to make it a low 6 second in 1/8th bracket car. I will not use the nitrous the kit. I was disappointed at my first test at track,,we're sea level here in Florida. 7.01 98.6mph, 11.00 at 120mph 1/4,had to leave above idle off ft brake. The trans solenoid wasn't working when I went to stage,,. The car is about 3200 me in it. I really thought she would go 105-110mph without the nos.
I just started dissecting what I bought and found a low fuel level both ends of holley,, lashes from .026-.035",,,timing at 30*(apparently for the nitrous),,,and a Howards 111113-12s big bottle nitrous roller cam. 263/273 .682/.688 with 1.6 rockers and 112 lobe separation ground 4 degrees advanced.
Is the cam holding the engine back since I'm not on NOS ??? How much???


Brian

more specs I know..

434 with ross flat tops, tall single plane Pro comp intake and 2" spacer along with the 300 nitrous plate. 835cfm pro systems carb, 110 gas, Pro topline 235,64cc chambers,2.08/1.6. unported heads, 4.56 gears and spool. PG with 5000 convertor and trans brake.

I bet even with a 100 shot that car would run into the 9s.
I understand its a new car for you so plenty to look at and enjoy the ride.
A couple of things in my opinion -
A specifc nitrous converter will kill a NA set up
You have around 10.5:1 compression approx,I have run so called nitrous cams in NA form and found with the more duration and earlier exhaust opening wider LSA was turn more rpm 7500 plus to make it respond with lower compression.
The as cast cylinder heads and intake will certainly hold back potential power as well.
A bigger header might help but there are other things to consider first.
If a 100 shot didn't show more than 100 hp output there might be a combination issue hence my first comment.
The car should mph regardless of leaving at idle or higher rpm if converter is working correctly, I have found in the past if a car 60 ft better with same combination it will take a small amount of mph off at the big end

[Monza355]

I bought a street racer monte carlo. I'm trying to make it a low 6 second in 1/8th bracket car. I will not use the nitrous the kit. I was disappointed at my first test at track,,we're sea level here in Florida. 7.01 98.6mph, 11.00 at 120mph 1/4,had to leave above idle off ft brake. The trans solenoid wasn't working when I went to stage,,. The car is about 3200 me in it. I really thought she would go 105-110mph without the nos.
I just started dissecting what I bought and found a low fuel level both ends of holley,, lashes from .026-.035",,,timing at 30*(apparently for the nitrous),,,and a Howards 111113-12s big bottle nitrous roller cam. 263/273 .682/.688 with 1.6 rockers and 112 lobe separation ground 4 degrees advanced.
Is the cam holding the engine back since I'm not on NOS ??? How much???


Brian

more specs I know..

434 with ross flat tops, tall single plane Pro comp intake and 2" spacer along with the 300 nitrous plate. 835cfm pro systems carb, 110 gas, Pro topline 235,64cc chambers,2.08/1.6. unported heads, 4.56 gears and spool. PG with 5000 convertor and trans brake.

I bet even with a 100 shot that car would run into the 9s.
I understand its a new car for you so plenty to look at and enjoy the ride.
A couple of things in my opinion -
A specifc nitrous converter will kill a NA set up
You have around 10.5:1 compression approx,I have run so called nitrous cams in NA form and found with the more duration and earlier exhaust opening wider LSA was turn more rpm 7500 plus to make it respond with lower compression.
The as cast cylinder heads and intake will certainly hold back potential power as well.
A bigger header might help but there are other things to consider first.
If a 100 shot didn't show more than 100 hp output there might be a combination issue hence my first comment.
The car should mph regardless of leaving at idle or higher rpm if converter is working correctly, I have found in the past if a car 60 ft better with same combination it will take a small amount of mph off at the big end

Typical 434 with flat top piston and 64cc chamber head normally has around 12:1 compression +/- 0.5:1 ratio.

5000 stall converter you say. What size is it ? And is that stall rating based on any amount of nitrous ? How does it recover after the shift ?

[PRH]

I wouldn’t make any big changes to the combo without having the car at the track for a few outings.

Go through all the normal tune-up areas.
Timing, lash, jetting, etc.

I’d experiment with removing the carb spacers, shift points, launch techniques, etc.

Once you’ve gotten all that sorted out, and the predictablity is pretty good, then you can assess the overall combo and start making changes.

I’d try and get a good idea of what the true flash stall speed is.
Is it actually 5k? Or?

The Moroso slide rule shows 11.00 and 120mph lines right up with each other.
The bad news is that for 3200lbs that only works out to 425hp.

You’re pretty far away from the goal of a “low-6”(upper/mid-9 in the 1/4).
You’re looking for another 200hp+ in performance.

[6.50camaro]

I agree with PRH go over the basics . You said you had 1-3/4" headers are you running full exhaust ?
Just to give you an idea as to what you should be able to do. My car is a 72 camaro leaf spring caltrac bar is 3150lbs with me .
422 sbc flat top 64cc chamber 11.6 to 1 CR ,old dart 220 race heads measured at 225cc 2.125 ,1.625 valves , .675 in .645 ex lift 260/268 @ .050 107 lsa installed at 104 icl . 850 Holley Street HP carb with only secondary jet increase 4 sizes and squirter change to eliminate bog off the line .1-7/8" Hooker super comp headers. 5500 stall converter 4.56 gears PG with brake two step set at 3200 rpm . The best I was able to run before slowing it down for 6.50 index racing was a 6.31 @ 108 .31 , 1.38 60'. Best time was at 32 degree adv. timing . it went 6.36 at 34 degrees adv. .
Your wider LSA will take some bottom end out but with a 5000 stall converter your not down there anyway .
Best wishes with tuning. it can be a long process . change only one thing at a time so you can determine if it worked or not .Dan