99+ intake conversion vs. cold-air vs. snorkel-air

Okay,

Just trying to understand some things here.

If I was planning on adding the snorkel to my 97 XJ and running that right into a big cold air cannister, etc...is there any reason to do the 99+ intake upgrade? Am I talking two different things? Is the 99+ intake conversion just a cheap way of getting more power with doing an cold-air intake?

Kinda confused over here

Thanks,

Chris

what i believe you are referring to are two completely different "upgrades". while you will find that there are differing opinions on the benefits of both of these modifications, the "claimed" power increases for the 99+ intake are far greater than that of a snorkel (20-25hp compared to 5-6hp). the 99+ intake is referring to the actually swap of the intake manifold, not the air filter/intake. the benefits of a snorkel are more visually obvious (higher air intake, some deep water crossing benefit, and a mild ram air effect). the newer model intake manifold, while still not a very difficult DIY job, doesnt seem to have been justified as of yet. i'm unaware of anyone doing a before and after dyno. i myself have been curious about both of these mods (i threw a rod in 4.0 yj when i was 18 after a water crossing, and i picked up a newer intake manifold for $50 after all was said and done) i will try to get my jeep dyno tested to figure out any gains. but wont be able to have this done for a month or so.

basically, if what your looking for is more power, anything that increases the volume of air to or from the engine is going to give you some mild gains. the consensus is that the most bang for your buck will come from camshafts, stokers, etc. try doing a search, there have been several discussions about this .

Yeah...that makes more sense. I wasn't sure exactly what was completely swapped, but now I see the difference. So I am wondering if you can still add a cold-air intake sytem or larger intake system along with the 99+ intake swap for more air volume?

Thanks,

Chris

i dont see why not. the only differences in the newer intake manifold is the larger volume (also more rounded appearance) and the newer injectors/fuel rail. like i said, i should be doing the new intake soon. i'm going to add a throttle body spacer and a 62mm throttle body. expecting 10-15hp gains, but the "claimed" 20-25hp would be nice too. eventually, i would like to add a snorkel/air canister. i'm a little scared of that river still.

Be happy if you gain 5hp from the '99+ intake manifold swap, never mind 10-15 hp or even 20-25hp. The only differences between that manifold and the earlier type are the larger plenum and the curved runners. The runners themselves are the same diameter and virtually the same length so there isn't going to be any HP increase from there. The larger plenum does move the HP/TQ peaks to slightly higher rpm so there may be a small HP/TQ gain from there. On the other hand, the larger plenum produces a weaker vacuum signal (so the brakes won't feel quite as powerful) and throttle response is slower.
Until I see dyno results showing a significant HP/TQ gain from the newer manifold, it's hard to justify the expense of buying it together with the PS pump bracket and going through all the hassle of making everything fit.
Gojeep did this conversion on his XJ and he only noticed a slight SOTP change if any.

So let's guess that you only get 5 hp...is there any other reasons or advantages to do the swap?

Chris (Double Down)

Not really unless you like the looks. It does save a little bit of space and that's about it.

Like Dyno mentioned, I haven't seen any actual before/after tests done with this swap either, although I've read quite a few threads where people were happy with the results after making the swap. I'm planning on installing the newer style, along with some exhaust upgrades as soon as I finish porting my HO head and then I'll let you know what I find if you like.

Only problem is it will be hard to say exactly what improvements the swap will do for me, because I'll be installing the exhaust upgrades at the same time. (Mike Leach header, 2.5" high flow cat and Magnaflow muffler ending with a 2" tailpipe.)

Good deal, let me know what you get. I am getting newer upgrade with the exhaust but not the header, so I will have an idea what the exhaust will do...just let me know about the swap.

Thanks,

Chris (Double Down)

Geez, what a teaser. Used the search button and I get some discussion, but no results? Come on!

I don't think a snorkel will give you any performance as far as more HP. All the tight bends, long runs, and narrow tubing aren't doing anything for airflow. What it will do is protect your engine from water damage, obviously.

Double Down said:

So let's guess that you only get 5 hp...is there any other reasons or advantages to do the swap?

Chris (Double Down)

Click to expand...

As someone who's actually done this conversion I think I can give some feedback. Prepare for some reading ahead. :compwork:

My 92 XJ was, engine wise, bone stock when I got it except for a cheap open element air intake system and 2.5" cat-back exhaust. It was a PIG. No power at all. I just thought it was the 31" tires and wheels slowing it down. I started to change a few things to my liking and here's my impression of each one. No dyno results, but it's my DD so I noticed everything I did.

First thing I did was get rid of the open element intake system and put the factory air box, inlet elbow and a cheap Fram air filter. RESULTS = Major difference in response and power. I had cleaned and oiled the air filter so it wasn't clogged. My theory was it was just sucking hot air from under the hood. The factory air box gave the engine some fresh air.

Next step was NGK plugs and Standard cap and rotor. RESULTS = Smoother idle, better response and driveability.

This next step was a big one. I figured, since I had the intake off I might as well do a header too. So, I put on the 99-up intake manifold, P/S pump, new drive belt, T-Stat, APN header, 49psi fuel pressure regulator and Mustang injectors. Not the CORRECT injectors though but I got them for free and mine had 162k on them so I threw them in. RESULTS = I couldn't believe the difference. I figured it MIGHT be noticable from what everyone has said, but it was NIGHT AND DAY different. Keep in mind that I'm running too much fuel pressure for these injectors, stock throttle body still and stock pipe from the header to the converter. But it was worth every penny.

The next step was replacing the only stock section of exhaust. I had a local shop bend up a 2.5" pipe from the header to the converter and also added a flex pipe under the oil pan. My theory is the lack of flex section combined with the constant strain on the drivers mount (mine was broken) from wheeling/torque is one of the causes of cracked manifolds. Anyway. RESULTS = Slightly different exhaust tone but not anything noticable on driveability.

I'm almost done so stay with me.

The next step was a home ported throttle body. RESULTS = scary throttle response! The first time I drove it all I could think about was, "How am I going to slightly blip the throttle over rocks if needed?". But now that I've driven it a while I'm used to it. But it was noticeable and worth it.

Final step, where the XJ is at this point at least, is the correct 4-hole NEON injectors. RESULTS = Smooth idle. Noticable change in throttle response and driveability. I just did this so I can't report on gas mileage yet. But I haven't LOST any with the previous mods so I don't expect to with this one.

Would I do any of the above mods again on another Jeep? In a heartbeat. I've even put off the 4.10 gears until later this year because of the power it's got now. In fact, my buddy is putting an engine in his and we're gathering the same parts for it. Now, as you can tell, it was more than just an intake manifold swap. But like any mod you do to an engine, you have to add the support pieces or you won't see any changes.

Hope this was helpful.

Talyn said:

I don't think a snorkel will give you any performance as far as more HP. All the tight bends, long runs, and narrow tubing aren't doing anything for airflow. What it will do is protect your engine from water damage, obviously.

Click to expand...

I agree with this. The best setup would be a 'cold air' intake for performance, or some sort of cowl induction like GoJeep has that is low restriction.

I was referring to intake manifolds in asking for good results. HO vs 'New' (can we call them 'Power Tech' manifolds).

I've seen one thread cut-n-pasted over several sites where a guy with a grand cherokee gained some power and proved the Power Tech manifold flows better with a shop vac and some backyard engineering, then JP magazine runs a dyno test and says that they gained no HP and lost a little torque.

I've seen that thread and i believe it had dyno results as well. IIRC he also did some grinding on it.