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Nitrous questions: 2.8 by notaguru
Started on: 05-07-2014 10:02 PM
Replies: 8 (277 views)
Last post by: mcguiver3 on 05-08-2014 02:34 PM
notaguru
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Report this Post05-07-2014 10:02 PM Click Here to See the Profile for notaguruClick Here to visit notaguru's HomePageClick Here to Email notaguruSend a Private Message to notaguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
'88GT 2.8L auto trans, 40k miles and stock except for improved exhaust manifolds (Thanks, Ray).

I've had nitrous in several cars over the decades with great success, using it only rarely. For this Fiero and the way I drive, that would cost only 5-6 pounds a month. It'll be a wet system with auto bottle opener. With the bottle in the trunk the NOS line will be very short. A false bottom in the trunk will make it stealthy, too.

The 2.8's power curve suggests spraying at 2,000RPM and nearly WOT. If I do a 5500RPM rev limiter, stresses should be pretty low, and the car will certainly be fast enough. I was told that GM planned this engine to support displacements up to 4.0L and HP up to 350. If that is correct, it should be pretty strong, and able to support an occasional 100 shot.

Questions:
With this auto trans, what are the speeds in each gear corresponding to 2200RPM and 5500RPM?
Is that 4L/350hp story correct?
Will the stock injectors handle the extra fuel (fuel pump and filters are new and ok)?
Have others had problems, blown engines, etc. with a 100 shot?

THANKS!!
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racingfortheson
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Report this Post05-08-2014 01:38 AM Click Here to See the Profile for racingforthesonSend a Private Message to racingforthesonEdit/Delete MessageReply w/QuoteDirect Link to This Post
I would like to run a 50-75 shot too, but there seems to be a lot of people here who think NOS is the worst idea ever. Problem for me is I would use it for sure. I drove the car today and on my short trip I burned 1/2 a tank cause I was playing around and keeping my foot in it. So I'm sure NOS would be a bad idea for me. If there is a way to run it safely then I'm in on that.
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RayOtton
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Report this Post05-08-2014 08:39 AM Click Here to See the Profile for RayOttonClick Here to Email RayOttonSend a Private Message to RayOttonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Henry, the funny thing is I was doing preliminary research into this very subject just last week.

I know very little about nitrous other than it's a cheap power added with some bad downsides if not done properly so I'd be interested to see where this post goes. Seems like you're light years ahead of me on this since you've already done it in the past.

Oh and expect that within ten posts someone will tell you to just drop in XZY engine rather than fool with the 2.8.
( See the long line of similes - JOKE )

If you don't get any useful info here I'd be glad to join up with you outside of Pennock's to see what we can do.
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hookdonspeed
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Report this Post05-08-2014 10:39 AM Click Here to See the Profile for hookdonspeedClick Here to visit hookdonspeed's HomePageClick Here to Email hookdonspeedSend a Private Message to hookdonspeedEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by notaguru:
I was told that GM planned this engine to support displacements up to 4.0L and HP up to 350. If that is correct, it should be pretty strong, and able to support an occasional 100 shot.


same "basic" block design as the 3900 engines, so that is semi true, as they had to make alot of modifications to get to the 3900 engines. and the 3.6: VVT engine is also an "offspring" of the 2.8 that being said... you can put NOS on the 2.8 but dont expect a 30 year old engine to holdup very long. and 100 would be pushing its limits ALOT. 50shot might be ok for a bit.
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RayOtton
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Report this Post05-08-2014 11:01 AM Click Here to See the Profile for RayOttonClick Here to Email RayOttonSend a Private Message to RayOttonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Here's a question. Is there a possibility of anything LOWER than a 50hp shot?

Not knowing to much about this I'm just wondering if a 25 to 30 hp boost would be doable. I realize it wouldn't rip the rubber off the tires but a nice little extra oomph in some situations would be nice.
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rogergarrison
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Report this Post05-08-2014 11:07 AM Click Here to See the Profile for rogergarrisonClick Here to Email rogergarrisonSend a Private Message to rogergarrisonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Id think lower settings wouldnt be that bad. Make sure you have a good condition engine to start with. Fiero autos dont take much abuse. Theyre 'adequate' for a stock 4 cyl or 2.8.
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RayOtton
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Report this Post05-08-2014 11:19 AM Click Here to See the Profile for RayOttonClick Here to Email RayOttonSend a Private Message to RayOttonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Well, it's only got 45K on it and the prior owner was literally a little old lady. ( Not from Pasadena )

Plus I'm a pretty sedate driver in the Fiero myself. A little kick in the pants is all I'd need.
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notaguru
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Report this Post05-08-2014 11:20 AM Click Here to See the Profile for notaguruClick Here to visit notaguru's HomePageClick Here to Email notaguruSend a Private Message to notaguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
FOR THE INTERESTED AND SKEPTICAL

Most nitrous horror stories come from situations where people try to add 250hp to a system (engine, drive train, driver) that simply won't handle it, or build a system that lets the engine run lean. Also, there are THREE different approaches, based upon what happens when the hammer is going down.

WET systems spray gas when or even before the nitrous begins. A good design ensures that the engine never goes lean. DRY systems spray only nitrous, depending upon the O2 sensor to tell the computer to add gas. The engine doesn't need to run lean for very long to be damaged.

Assuming a wet system, there's also the matter of WHEN nitrous and gas are sprayed. It cannot be done at low or max RPM - there's a "window" in which the added power can be handled safely. Therefore, a good installation will include a (great name) WINDOW SWITCH that prevents nitrous outside a preselected range.

For more than a 50hp shot, even in a wet system, there should be other modifications to improve functionality and reduce risk of damage. The third approach is WET plus OPTIMIZATION.

One must consider the fuel system and the exhaust. The injectors (supported by a competent fuel pump!) must flow enough gas to avoid risk of any cylinder going lean. I just installed a new fuel pump, screen, filter, and WIRING to ensure fuel adequacy. Also a big nitrous shot will generate a lot of exhaust gasses, and some stock systems won't flow it - creating back pressure and the probability of (valves, I think) damage.

Some drivers will keep the bottle's valve open at all time, because every stoplight is an opportunity to spray nitrous and testosterone - a dangerous combination. I've met people that go through more than 50 pounds a month! I've never used more than 10 pounds in a month, including a trip to the drag strip, and in most months my usage is less than 5 pounds. If a conservative driver uses nitrous only occasionally/properly, a solenoid-controlled (a motor is too slow) valve is important. I used TPS data to open the valve when the throttle reached a selected point beyond normal acceleration, and read RPM to spray only within my preselected RPM+TPS range. When I backed off on the throttle and returned to normal TPS range, the valve would close. There are a few cars in this area using that configuration with good - and safe - results.

A nitrous system on the 2.8 will do more per dollar than an engine upgrade. That's an easy +100hp for $500-600, and in the Fiero the installation would be virtually invisible yet removable in 15 minutes. Also, when not "on the bottle" you will have the same fuel efficiency as before nitrous, while a big engine will burn more fuel at all times.

I talked myself into this... it'll be my summer project for this evolving '88GT.

[This message has been edited by notaguru (edited 05-08-2014).]

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mcguiver3
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Report this Post05-08-2014 02:34 PM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Edit/Delete MessageReply w/QuoteDirect Link to This Post
So...
notaguru do you have a parts list for this?
Schematics for installation?
We neophytes need some pictures, drawings, lists, help.
I too am interested.My autocrosser is an 88 2.8 5 spd.
Everything has been eliminated, removed, modified on this car.
Could be what I need for an edge.
The intake by definition is open for me in my class.

Bob D
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