Cubic Inches VS Nitrous

[Guest]

[mrdodge01]

Looking for some expertise here on smaller cubic inch applications.  Little background info....

My combo starts off with an A4 block, .060 over, 3.4" crank for a monstrous 352 cubic inches, lol.  Eagle forged crank/H beams, JE Slugs (10.8:1) wrapped with Hellfire rings.  TEA 185cc twisted wedge heads, with a billet core custom hydraulic roller, mild n20 camshaft.  Unported vic. jr intake, 850 annular mighty demon.  Spraying with an NX shark nozzle direct port. 

Seems that nobody around my neck of the woods is spraying anything really hard on engines less than 400+ cubic inches.  The class racers with their 4.125 or larger bore, 4" or larger stroke motors stuff 500, 600, or more hp worth of n20 down their throats, but I can't seem to find anybody successfully cramming large amounts down a smaller motor...  Any thoughts? 

I've sprayed 26s (200) and 31s (300) and picked up 260rwhp on the 200 and 358rwhp on the 300 on a local "heartbreaker" dyno.  This is through a c4, and the little turd made 355rwhp n/a through it, so I'm not really taking those numbers to the bank.  I'm wanting to pill it on up next year, but at what point do you call it a day?  I've used the old "pill it till you kill it" line on a stock shortblock before, but I do have a decent chunk of change invested in this one, and I'd rather not kill it if I can avoid it, lol. 

[juiced coupe]

At this point, you are doubling your NA power. I'd say that you have about reached the limit of your combo.

Past 300 with a short piston, you'll probably need to look into a custom nitrous piston with a thin ring pack.

[woody]

A customer of mine sprays 3 stages for a total of 675 on an A4 blocked 308 inch. 8teens car. You wont hurt the block, you will hurt a piston though

[mrdodge01]

I'm not too concerned with the dyno numbers... That makes me feel better about the block decision- I found a good deal on this one, and a few friends of mine are telling me that I need to find an R block, because my A4 won't last.  Really I'm trying to figure out if I can get in the 8.90s with this combo...  Sorry for the huge post, but more info is better, right? lol

I've only made a couple N/A passes... after I made my best pass I took the car to the dyno the next day, and with no changes from the previous nights setup it only put down 331rwhp.  The carb was lean, so we jetted it up some and it was low on timing, so after we messed with it we ended up making 355rwhp. Might be more there, not sure.  Max timing that we tried was only 32 degrees, then we started spraying it. 

My n/a best is:

1.742 60'
4.840 330'

7.408 1/8
95.647 mph

11.512 1/4
118.774mph
http://www.youtube.com/watch?v=iN0F5O9109k


And I've also only got to make 3 N20 passes, first of which I had the progressive way too agressive, and it unloaded the tires...

http://www.youtube.com/watch?v=yMf-Xmwg9to
9.88 at 141

Then at the local street car race, made two more passes... track sucked, so I left at 25% held out for 5 tenths, then to 100% over 1.4 seconds total.

http://www.youtube.com/watch?v=0fgqRGHoHho
9.75 at 141.9

Turned the progressive up to 40%, same 5 tenths hold, then to 100% over 1.3 seconds total

http://www.youtube.com/watch?v=qjo2qfM7EqQ

1.454 60'
3.971 330'

6.089 1/8
115.971 mph

9.520 1/4
140.209 mph

This was on a 28x11.5 MT Bias ply ET Street (cars had to have DOT Tires) and I'm buying some 28x10.5 stiff sidewalls for next year so I don't have to baby the thing out of the hole so much. 

[Blk88GT]

IMHO.....

Work on the 60ft then apply more up top. You'll need ~150mph to pull the 8. Try to get the power in as soon as you can then work on the hit %. I spent all season bringing in the power sooner, then backing it up so I had data to go off then I started playing with the hit %. Your 60ft is way soft for the ET.

It may have taken me longer than most, but I don't have a huge budget and I did it across 3 different tracks. I have my good, bad and ugly scenarios covered if I need to make a hit somewhere new

What size wheel is that? It looks small compared to the tire.

I run a 418 with a small plate on it but I run a glide and 275 radials.

[mrdodge01]

The rear wheels are 15x8s w/4.5" backspacing.  One of the things I'm looking for this winter is a set of 10" rear wheels to mount some 28x10.5 stiff sidewall M/T ET DRAGs, so I can get the 60ft down without all the hassle of baby steps with the progressive, lol.  I'm not sure how much room for improvement there is ET wise with, say, a 1.30 60ft, but that alone isn't going to be good enough for 8.90s.  The next step up in my n20 jet box is from the 31s (300) to 35s (400)

[Blk88GT]

It also seems you are down MPH on the top end, IMHO.

[mrdodge01]

Yeah.... combination of a fat tuneup and nowhere near enough timing, plus my crankcase ventilation system wasn't exactly up to par, and the car was pushing oil out around both valvecovers out the gaskets on all sides- it went 142 on the pass before that... I'm gonna work on the tuneup some more (needed a jet change, didn't have any odd sizes to go up on the nitrous or down on the fuel) And put timing in the thing, it did feel lazy on the big end though. 

[Induction-Solutions]

I have a customer with a 360 incher that hits it with a single stage direct port with around a .042 nitrous jet in it. has been very reliable in his EFI combo.. Thanks, SJ

[mrdodge01]

That's what I've been wondering, just looking for some real world usage of large amounts of n20 on a smaller motor... Now for my next q.... Say I've maximized the output of the car on this current jetting and want to step it up... would it be better to just step up the jets on the fogger kit or to add the extra power with a second kit?  I have an NX pro power conventional plate kit fed with some NOS Cheater solenoids on the car, just haven't used it so far... What are the pros/cons of upping the fogger vs. 2 kits?

[Studly]

two smaller kits are usually faster than one single large kit, but getting the fat out of the tune up and getting the car to run is more important than spraying large numbers. my 383 sbf stock block .030 ran 8.91 @150 mph and it should have ran faster had the tune up right just not the suspesnion 1.34 60 foot chest high with a c4 and 411 gears

[Blk88GT]

x2 on the 2 kits rather than one maxed out one.

[Rotax]

Any updates?