Hi guys, I plan to add nitrous to my 305. It's got a stock bottom end with a Mellings HV oil pump, ported stock heads, small crane cam etc. Best ET is as per my sig.

What is the maximum nitrous shot that I can *safely* add? Is a 100 or 150 HP shot too much for a stock bottom end 305?

I plan to upgrade my fuel supply with a Vortech T-Rex inline pump, b4 running the N2O.

Any opinions? Thanks

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1987 Chevy Camaro IROC-Z. 305 TPI. 700R4
14.6 secs @ 93 MPH.
2.14 sixty foot.
Homepage

 

Jim,

Tim Burgess has been running a 90 shot for years on his stock-bottomed 305. We both know how hard he drives his car at the track.

Here is my hypothesis on how much nitrous you can use: Tim runs low 12's with a 90 shot. Tim's car is unique in the sense that he runs high 12's naturally aspirated. I don't know of any other 305 that can make this claim. I for one, do not come close. So he definitely has a huge head start. A given amount of stress is induced on the engine (bottom end) when running low 12's. Unlike Tim's car, it will most likely take much more than a 90 shot to equal his times. However, the stress induced on your bottom end will be the same as in Tim's car, given the same end result (low 12's). Therefore, I firmly believe that you will be able to use even higher levels of nitrous in order to get your car down into the low 12's.

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
12.57 @ 111 mph.
12.04 @ 114 mph (50-hp nitrous).
http://members.optushome.com/au/downunder1/rides/willie/willie.html

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

[This message has been edited by Willie (edited January 27, 2001).]

 

I have a 127k mile 305 in my 91 TA. Last season we were running a 120 shot to it and made a best pass of 12.38@108,and we had it jetted WAY too rich.With tuning i believe we can knock another 1/10 or 2 off.Also I tried hitting it with a 160 sgot,and it ate the clutch.
This year i am going to install shorty headers/3" cat back/3.73's/new clutch. Hoping to get into the 11's with the nitrous,and I really dont think ill have a problem.On motor it ran a best of 13.44,the car has a LOT of wieght removed(the only reason i can figure out it does run so good).

Dirk

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1991 TA WS6 305/5 spd
Nitrous,hooker shorties,flowmaster 3" cat back,3.73's and a 160 shot of nitrous
DragStars 15x3.5 et fronts,15x10 rears with 275-50/15 BFG DR


1997 TA LT1
Draglites,15x3.5 sportsman pros
16x9 255-50/16 Comp TA's or Drag radials
Moroso CAI,no sway bar,dynomax non catback

 

I've seen from some sources that a 125 shot is about the highest you want to run on a stock 305. *Don't quote me on this though!*. Make sure you get a throttle switch or a nitrous computer like the Jacobs Electronics Nitrous Mastermind to help prevent any problems.

 

I have a 125 shot on my 305 TBI and have gone through approx 10 bottle fills by now and have not had a problem. Just make sure you run colder heat range plugs and maybe retard the base timing a couple of degrees.

 

I have run 150 hp plenty of times.Iv'e even steped up to 175 hp now.The two most important things to remember are timing and fuel.
When I get this thing tuned right,(heads flow like ****)I should be in the mid 11's.
Then I'm going to see If I can be the first around here to run 200HP in a stock bottom
305.Maybe

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1990 Trans Am WS6
305TPI 700R4

ENGINE:
150hp NOS kit
March underdrive pulleys
Edelbrock headers(JetHot)
Mac off-road pipe
Flowmaster exaust
Jacobs ultra coil
K&N filter
Fulley ported base,
runners,& plenum
Crane AFPR
Hypertech airfoil
Crane 1.6 rockers
210/220 .533/.544 Cam
W/P Torquer heads
Edelbrock TPI Base
Edelbrock TI Runners
Edelbrock 52mm T.B.
TRANSMISSION:
Richmond 3.73's
Auburn posi
B&M Mega shifter
B&M Transpak
Vette servo
B&M 2400 converter
TCI Trans Rebuild
Nitto Drag radials
FUTURE MODS:
The 700R4 is DEAD!!
Neeed to rebuild AGAIN!!
BEST RUN:
12.48 @ 109.23 MPH
(with stock heads,cam,intake,and crappy Pep Boy's tires)

 

Thanks for the replies

Willie, I agree with your post re 305 bottom end. 12's should not be a problem, based on Tim's and your own experience.

Nitro Don, you have some awesome times there for stock heads and cam. Now I am worried about my 700R4! I think the trans may be the weak point for 12 sec passes. My trans was rebuilt 1.5 years ago, but it is stock.

 

What is the kit number for the NOS for a TBI...I would really like to know.

 

05153 (A,B)GM TBI, throttle body injection, 4.3L V6, 5.0L & 5.7L

05153-V6 (A,B)GM TBI, throttle body injection, 2.8L V6


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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

My IROC-Z
EFI Performance Club on Yahoo
Club IROC-Z