well guys thought I would update you on another modification I made to the car last night. Went with an Arizona Speed and Marine 1350CFM MonoBlade.

Took the car out last night after cutting the partition out of the intake. The difference is SCAREY. I am usually not one to get very excited over little things, as they normally do not make much of a difference, but this definately improved throttle response, and overall made the car pull much harder! I mean much much harder.

I was shocked at the difference, since corky put on on his, with the MAF, and he gained about .12 sec in the 1/4 with it. However he said it "felt" the same. Mine however is running the SD system, and I think we might have just uncorked the bottleneck on these setups. I was utterly amazed at the difference. My fun was cut short with a huge storm.

I did change the gearing also from 3.07=>3.45s with the spool, but I drove the car home after the gear change about 8 miles, and played with it. With the 29" tall tires on it, the gear change is nearly un-noticable. But this Throttle body made a tremendous difference.



This one here is blue, ours are billet polished aluminum. Very much like the holley unit I had before, but a little nicer, and of course larger.

Car and driver put out an article a little bit ago with comparing different TBs on large CI motors. They gained about 20-30hp from 1000CFM to 1300, and another 20-30 with moving up 2000CFM. I am sure I am not quoting the numbers perfect, but our motors are larger than the one tested, so the gains should be even better. Still might not have enough TB though.

However, as I always say. The proof is in the pudding. Or rather where the rubber meets the road. Tonight, if this friggin weather co-operates, i am going to take the car to Keystone for some T & T. I think the results will be pretty favorable. But time will tell. :smash: :cheers:

 

I don't doubt your results but the math tells a different story if I did it correctly. Be aware that I may well have done it incorrectly so correct me if I'm wrong.

Your engine displaces 434 cubic inches. 1 cubic foot is equal to 1728 cubic inches. This means that your engine displaces .251 cubic feet of air. For each revolution, half of your cylinders are on the exhaust stroke, half are on the intake stroke. This means that for one revolution you only need half of this air or .126 cubic feet of air.

So if one revolution requires .126 cubic feet of air and you're turning 6000 RPM's, that means you need 753 cubic feet of air per minute, which is roughly half of what your TB flows. This also assumes that your engine is running at 100% efficiency, which simply doesn't happen.

It's very possible that the car feels faster because for every little bit of throttle you are flowing more air, which feels like faster throttle response. The problem is that the upper end of the pedal travel is useless because TB is already flowing the maximum amount of air the engine needs at say 50% throttle.

Now all this being said I would love to see some dyno results. Track times are good test but I still don't find them as convincing as dyno runs. Even the most consistent driver can have greatly varying track times based on conditions.

Keep us updated.

 

It would have been nice if you went to the track with just the 3.45 gear change and then again with the new TB installed. Unless I missed a thread.

 

Guys.

nathan. Not sure if you can look at the air flow of a motor in that sorta simplicity. That anaylses is using a snapshot (static) point of reading and basing it on that. However we know that the system is VERY dynamic, ever changing so we might not be getting an accurate anaylses.

Put it this way, if you talk to anyone at a track with a 400+ inch motor, most likely with lesser heads, they will be sporting a 1200+CFM carb on the car. Granted that is a wet system, and ours is dry, which also wasn't taken into consideration in your analysis (but would help your argument).

In addition, I whole heartedly DISAGREE with your dyno comment. I will bet dime to dollar that you will get more accurate accessment from track results, looking at the last 1/8 mile interval than you ever will on a dyno.

Take a look at how much dyno numbers vary on the forum. Anyone that using these numbers as a true measuring stick is going to be very lost. Look at our 406s. Corky's dynoed 377rwhp went 10.90, mine dynoed 433rwhp, and went 11.02, side by side on a track, yet they ran identical through the year.

Scorp the gears should help some, but when doing the math, the 3.07=>3.45 gear change is not a whole lot with the addition of 2" to the tires. they are about 1/2 what they should have been with 26" tall tires.

In the nutshell you all know how I feel about these automotive calculations.

:rolleyes:

 

Hmmmmm! forgive me up front-I haven't got my thinking cap on this AM, but are you sure half is on intake and half on exhaust? what about the comp. and combustion strokes? :confused:

 

Nathan,
I had always used similar calculations to size carbs. I would generally factor in 80-85% VE. It seemed to work pretty well for street, only, cars. I don't know the reason and have no clue for a formula, but I have never (maybe I didn't do it enough times) put a bigger carb on a race car that it didn't run faster. I had an old '66 Chevelle with a very mild, streetable, 454. I'm guessing it was about 400 hp. I switched out the 750 for an 850 double pumper. Everyone said it was waaaay too big. It'll bog, especially with an 1800 stall converter. I was able to tune the bog out of it by manipulating the accelerator pump and shooters. After that it was front tires off the track and low 12's every run. All THAT was with 25 year old technology. I agree with your reasoning, but the theory breaks down in practical race track application.

RACE ON!!!

 

Just to simplify it, a four stroke engine takes two revolutions of the crank to complete a cycle. Therefore, there are 4 intake strokes per revolution. The engine ingests half it's capacity every single revolution.

RACE ON!!!

 

What did you pay for the monoblade? Great job out there testing all these mods.

 

Instant message sent on your old T/B... Opps you have a 89 vette


[Modified by Corvette0096, 8:59 AM 5/26/2004]

 

Huh? Now I'm really confused (as if I wasn't confused enough already).

Jake

 

I won't disagree that there is more to racing than just the dyno. For what my car dyno's I should be running 11's, but there are a lot of other factors. All I'm saying is that to determine the effectiveness of a particular modification of actually increasing horsepower the dyno doesn't lie.

If you change throttle bodies while the car is strapped to the dyno and you get the exact same horsepower and torque curves the car will behave the same at the track. Now if you don't change the peak numbers around but it messes with the under the curve numbers it will behave diffrently at the track. Essentially you can't have just such a controlled environment at the track no matter how close the weather may be.

They dyno eliminates all of the variables except the power that the engine is making, which is what I'm interested in for a lot of mods. There are other mods such as gears or sticky tires that don't show up on the dyno per say but will make the car perform better at the track. These are just as legitimate but they are not actually making more power. That's why I'm curious to see what the throttle body does for the car on the dyno. The only way it can do anythig is if it affects the engine's power curve, which WILL show up on the dyno.

Track results are certainly valid, and ultimately they may be all that matters to you. You can't just say that a dyno is useless however because it tells the true story about your power.

 

Right, there are other "strokes" but look at what you just said. It takes 2 whole revolutions for the piston to complete it's cycle. This means that you have to divide the displacement in half to determine the air required per revolution.

I agree that it's an overly simplified idea, but typically over simplifications err on the plus side. Other things should decrease the maximum airflow, there shouldn't be a lot that can increase it unless you're running forced induction which will put you over 100% efficiency.

 

My car also really responded to the monoblade. I knocked about .15 off my ET, and picked over 1 mph


[Modified by tpi 421 vette, 11:42 AM 5/26/2004]

 

Ok, I've got a question: taking it to the next step, what to do about air intake? Will the TPIS set up you have Jesse now become the bottleneck? Seems like the engines are getting bigger and bigger yet we don't have a better way to get it from outside into the car? BTW, I hope you get down to M-D so I can see her run!

 

Hoover vette picked up .3 sec with the monoblade on a 401CI motor, and he was at 11.4sec! Not saying I will gain .3sec, but .2 might be realistic, with 2MPH, which would put me at nearly 130, in crappy weather :cheers:

I am for the time being, just running the TB open, no air tube, I think the TPIS setup will easily supply the needed air. :cheers:

 

can you post a link to that TB? does it come Mono Blade? and i guess i'd have to do some machining to my intake? looks awesome and i'd love to have a nice open path instead of it haveing to split thencome back together. looks cool and congrats.!

 

That isn't, "overly simplified" It really IS that simple.

Jake,
you're kidding, right?

RACE ON!!!

 

so in other words, all those threads where the regulars were harping on the bigger throttle bodies (and using math) are now in error? I've got a 383ci superram I'm working the bugs out of (can you say intake leaks? :rolleyes: ), and I figured the 48mm was considered to be appropriate. After all, they used them on some of the forced induction lingenfelter cars, right?

arg.

 

Raman,

I would not draw that conclusion, IN FACT, I would say that for 95% of the setups here 58mm is more than enough.

Remember what our setups are. And that I always say, Total package or parts that compliment one another. We have heads that flow 300+ CFM, INtake 300+ cfm, and now a throttle body to possibly match the above flows. I do not know of any easy calculations that tell you exactly what carb or TB you need. Again like the injector calcs they make assumptions. I usually tend to believe real world stuff more than calcs. If we all went by calcs, the top speed of a dragster would be at around 200MPH, instead of 330+MPH. ;)

Let me ephasize that I am not saying that everyone out there needs a 1300+ CFM TB. Save your money and get other mods, most likely unless you have some killer heads, and intake, something else will be the bottleneck.

Case in point. Your SR would NEVER need a 1300 CFM TB to cover the needed flow. At 260-270CFM, a 58mm is more than enough.

:cheers:

 

im using the same t- body on my car its a big improvment from the 58 mm good luck budd i think ull get the 10.4 this week :cheers: