Gen 2 to Gen 4 Engine Modification

[NI-KA]

what exaclty seperates the Gen 2 engine from a Gen 4 with these heads mounted on your Gen 2? i know 400cc's difference, but is it basically the same underneath the heads, and what HP are you aiming at? 500-550hp?

I am not an expert on the differences others may wish to chime in.
The crank stroke is greater on the later models. i.e. GEN 3 is a stroker when compared to the GEN 2. Same for the GEN 4. My engine is a standard GEN 2 crank.

Head air flow GEN 2 < GEN 3 < GEN 4

RPM GEN 2 < GEN 3 < GEN 4 the upgrade allows for GEN 4 RPM due to the more robust rockers & springs which allow for higher RPM

HP GEN 2 < GEN 3 < GEN 4

Throttle bodies:
GEN 2 dual bodies connected to pedal by cable
GEN 3 single body connected to pedal by cable
GEN 4 dual bodies connected electronically thru a wire to pedal (fly by wire)

The main bearings have been updated in my GEN 2 to allow for better oiling. This seems to be a fairly standard thing for all the viper engine builders to do. If your in there it is a no brainer.

I am hoping to get to 520HP+ Presently not exceeding 500HP which is disappointing. I have not had the budget or time to go to the dyno and have the tune worked on. 520RWHP SHOULD be doable.

The car has the GEN 4 fuel pump, larger diameter fuel lines, Bellanger headers and in theory plenty of air flow with the GEN 4 heads. I have my fingers crossed that with a little effort at the dyno the car will hit higher HP numbers. Unless there is an un-anticipated restriction in the fuel line (such as the after-market filter or pressure regulator) limiting fuel flow I am not sure what else could help.

 

[jasond29]

Are you running the stock cam? Less than 500 to the wheels with gen4 heads is almost impossible unless your missing some spark plug wires or something. I assume you have had it tuned?

 

[Roy]

that's awesome, the old looks with the new power! Some decent brakes on it and maybe some nice springs and it's good to go for another 20 years!

 

[NI-KA]

Are you running the stock cam? Less than 500 to the wheels with gen4 heads is almost impossible unless your missing some spark plug wires or something. I assume you have had it tuned?

Arrow installed a new cam since I have the old cam which I believe a stocker would be a 708 cam. Since the tune was updated I have not had the opportunity to take to the dyno to see if the numbers are any better.

 

[NI-KA]

that's awesome, the old looks with the new power! Some decent brakes on it and maybe some nice springs and it's good to go for another 20 years!

The car has StopTech brakes and Penske shocks.

By the way, I have a set of the GEN 2 (ACR) Dynamic shocks if anyone is interested.

 

[Viper Specialty]

The car has the GEN 4 fuel pump, larger diameter fuel lines, Bellanger headers and in theory plenty of air flow with the GEN 4 heads. .

If you just dropped that Gen-4 pump into the tank without modification.... you are going to be disappointed. There are a number of directions you could have gone, but dropping a Gen-4 into a Gen-2 without a very important set of modifications does not work out too well

 

[jasond29]

what are you letting the shocks go for? any pics of them? Thanks

 

[NI-KA]

If you just dropped that Gen-4 pump into the tank without modification.... you are going to be disappointed. There are a number of directions you could have gone, but dropping a Gen-4 into a Gen-2 without a very important set of modifications does not work out too well

Some mods were necessary in terms of putting the GEN 4 pump into the GEN 2 basket. This included developing a transition piece to replace the regulator that is part of the GEN 2 basket (new regulator went into the engine bay). The GEN 4 pump does not have an integral back flow so that when the engine is warm you have to "charge" the fuel system by cycling the ignition. Backflow preventer is to be installed.

The GEN 4 fuel pump was a recommendation.... naturally I followed the advice provided. As noted above it is not a drop in for sure.

If there are some other items - I am open to suggestions....

 

[Viper Specialty]

Some mods were necessary in terms of putting the GEN 4 pump into the GEN 2 basket. This included developing a transition piece to replace the regulator that is part of the GEN 2 basket (new regulator went into the engine bay). The GEN 4 pump does not have an integral back flow so that when the engine is warm you have to "charge" the fuel system by cycling the ignition. Backflow preventer is to be installed.

The GEN 4 fuel pump was a recommendation.... naturally I followed the advice provided. As noted above it is not a drop in for sure.

If there are some other items - I am open to suggestions....

Actually you took a different path than I had anticipated. I thought you actually dropped a complete Gen-4 module into your car- which we have done, and is technically possible, pending what year your car is; earlier Gen-2's are complicated with the filler on the module top.

I could not tell you for certain if you may have issues with your module without seeing it. But, Gen-4 pumps have no siphon. If you did not factor in the loss of that device, you will have fuel pickup issues. In your case, we would have taken an alternate approach, more than likely producing a part Gen-2/Gen-3 module. The Gen-3 pump flows more than enough for what you are doing. We have seen close to 700 RWHP on Gen-3 pumps with no issue, no booster, and no helping devices. The Gen-4 pump module really needs to be an all-or-nothing type approach, which is easier said than done for G2's.

We do a lot more with Gen-3 based pumps than anything else, as they are closer in design to the Gen-2 stuff and more interchangeable with them, and they also can be plumbed far easier for aftermarket scondary pumps. They are also capable of being fitted into Gen-4/5 cars as needed. The Gen-4/5 pumps fill a niche though, with a pump booster they are good for about 950 crank horsepower depending on needed pressure.

 

[NI-KA]

what are you letting the shocks go for? any pics of them? Thanks

Jason - I have over $1,500 in them which included getting them re-built. That said I would like to get them out of my garage.
e-mail is [email protected] this is not a primary e-mail for me. It will have to do since my account e-mail here is full.
Just post here when you send contact info. Pics are coming.

 

[Invasivore]

I wanted to share the engine build on my 1997 GTS. Just thought others might be interested.

The engine had been consuming a lot of oil. That with a frustrating vibration at around 1250 RPM which became noticeable after installing the woodhouse poly mounts finally convinced me to have the engine pulled and sent to Arrow Racing Engines.

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I did explore buying a used engine / bottom end to replace mine. I have not had particularly great success in purchasing used so even after finding a couple of possible candidates I opted for having the engine torn down and checked out. I couldn't bring myself to take the risk of buying a problem instead of a solution.

As it turned out the engine bottom end had a "few" problems:
a couple of rod bearings down to the copper
the crank was damaged and beyond repair
the cylinder walls were heavily glazed
and the oil pump/front cover was shot
at least the engine is numbers matching to the car


So while the bottom end is getting built back to stock performance a set of GEN IV heads will be going on the engine as well.


The bottom end will be primarily stock. A slight overbore to deal with the heavy cylinder wall glazing and a stock crank. There will also be updated main bearings which are the biggest thing to help out with the
oiling of the rod bearings.

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Naturally, all of this was very frustrating to discover and is really frustrating for my wife. She really enjoys going cruising in the Viper and the down time on this is not fun for either of us.

What oil were you running? Any speculation as to what caused the damage?

 

[NI-KA]

What oil were you running? Any speculation as to what caused the damage?

I ran the usual oil. However, the problems all started shortly after taking possession of the car.

The problems all rest with the previous owner. Water under the bridge at this point.
I inherited the problems.

I have extensively rebuilt this car with the intention of long term ownership.

To more directly answer your question: As I understand it the failure of the main bearings is generally a result of lack of oil.
The general enhancement to the bearings allowing greater oil appears to be a generally recognized practice so future problems should be mitigated. The stock oil pumps are sensitive to scoring of the aluminum housing. The main oil pump gears, I believe, are a harder metal but the housing being aluminum can be damaged and once damaged by any floating metal won't pump very well. I believe this to be the main failure mode. My opinion only.

Couple of other solutions/enhancements might be:
1. Dry Sump ($$$$$$)
2. Accusump (cost effective but not perfect - helps with pre oiling before starts and under surge/low oil pressure conditions; poor mans dry sump)
3. Swing arm oil pick-up (hoping someone like Arrow might produce one) doesn't currently exist.
4. Trap doors in oil pan around the oil pan pickup (I have installed in the larger oil pan) Aids in high "G" turns.
5. ACR oil filter adapter (Installed) Basically bypasses the oil filter under surge conditions.

 

[NI-KA]

what are you letting the shocks go for? any pics of them? Thanks

I do not have the ability to upload pictures here. E-mail me if you want pictures here: [email protected]

I will list on e-bay shortly.

 

[ACRucrazy]

Still following this thread. Still want a Gen II just so I can do this conversion LOL.

 

[Fatboy 18]

Hello NI-KA, could I ask, are you actually driving this car on the road yet? If so what is the seat of the pants feel of the car since the mods? Can you feel difference in speed pick up?

 

[NI-KA]

Hello NI-KA, could I ask, are you actually driving this car on the road yet? If so what is the seat of the pants feel of the car since the mods? Can you feel difference in speed pick up?

I can't comment directly with regard to your question since the car had upgraded heads that I sold before doing this. I can tell you that a friend (a real track rat) who previously owned a GEN 2 until recently was really impressed with the power the car put down and the seat of the pants feel.

 

[SingleMalt]

I hate to be one to crap here, but have you put some serious thought into cooling an extra 150HP? The stock water passages cast into the cover are anemic at best. If you plan to track and are making over 550 crank HP, it will become an issue for you.

Maybe you're able to use a Gen 3 or 4 cover, but I don't think that is possible. If you can figure a way, I would like to be the first to learn how you did it!
Trying to force more water around a Gen 1 or 2 cover to compensate will just create more pressure at the pump head.

Anyway, something to ponder before you run into issues.