To front mount or not to front mount; that is the question

[TTipe]

I support the use of a front mount for a couple of reasons. FACT; The first "intercooled GN mule" that was used by the "turbo" group was a silver 85 TType with a front mount intercooler. Most front mounts (due to size) have less of a pressure drop across the core than slic's generally. The PTE SLIC is an exception in some comparisons at ~ 1.5 psi pressure drop across the core. My front mount has about 0.7 psi drop across the core. The slic's are trapped in "an oven" or the engine compartment so where does the heat convection from the intercooler go?. Top of the line front mounts go through the traps with air that's ~ 20 degrees above ambient. The best slic that I'm aware of bangs the traps with air about 40 to 50 degrees above ambient. Work can be done to improve an slic's performance. Most slic's have less heatable mass than most front mounts (inspite of the slic crank pulley fan) relative to a short but equal amount of time stopped. The pressure drop across the core is more of a problem than a temperature drop across the core. Air mass is the most important concept. If my induction system causes the turbo to produce air at 25psi and my intake manifold only sees 21 psi then I cause my turbo to do work (which becomes heat) which reduces air density and drives the cylinder charge to knock. Alky sucks up a lot of that heat but is difficult to relate to the gasoline in the chamber. Stoich for gas & alky do not occur at similar ratios, nor are their burn rates the same. However when a calibration is written for a gas & alky car, the air fuel curve has a hook that pulls gasoline out expecting an alky replacement for that area under the curve since the alcohol is also consumed as a fuel. To me that's like pulling the pin on a grenade and not knowing how much time I have before it goes off. Obviously a lot of folks have mastered the art of explosion control (to a point) but I have trouble with the concept. FACT; the first GN mule used a cast iron radiused plumbing elbow from the maintainence stores to connect the turbo to the downpipe. Much less backpressure than the production released elbow from Garrett.

 

[TTipe]

Awwwwww, you made some good points and almost had me until you mentioned running race gas and pump gas. While using alky does take some extra monitoring, changing back and forth from a race gas tune to a pump gas tube involves a lot of work too. You'd need to drain all the pump gas out 100% to optimize the race gas tune, and race gas eats up O2 sensors and spark plugs so you'd have to check on them frequently. E85 seems like a good way to go but unfortunately its not available to a lot of people or not within a convenient distance. No matter what, when you start making a lot of power lots of stuff can fail and only by monitoring it all closely can you hopefully prevent a problem.

Going with the front mount may not be the best bang for the buck, but it should still help and alky may not be the best for everyone if you want to keep it simple. Like I posted before, search for some of my old threads to see what kind of tune I used to get the most out of pump gas with a TT chip.

Changing back and forth from a race gas tune to a pump tune with a file for each should be easy. You hit the nail on the head when you said "monitor it all closely".

 

[achalmersman]

Since this thread has broadened I would like to ask a question.

What would the expected gains be on a stock longblock car running a high quality FM (RJC 315?) WITH alky and 30ish psi? Going from stock non-dutt neck intercooler?

Are the gains (lower inlet temps and pressure drop) noticeable on a stock longblock in the 30 psi range? Love to hear a Bison response on this one....

 

[Mr.Spool]

Red

he best slic that I'm aware of bangs the traps with air about 40 to 50 degrees above ambient.

Red Armstrong makes 1000hp on a slic without alky and doesn't see that kind of intake charge temps vs ambient.

 

[Mr.Spool]

Alky sucks up a lot of that heat but is difficult to relate to the gasoline in the chamber.

These cars run great on pump gas alky and the single nozzle is easy to tune with the benefits of lower intake charges and more octane in the chamber.

 

[Mr.Spool]

I have run both front mount intercoolers and slic on and off alky.after seeing what the pte slic can do choosing an intercooler is a matter of preference only.

 

[V6sleeper]

Red

Red Armstrong makes 1000hp on a slic without alky and doesn't see that kind of intake charge temps vs ambient.

Correct, and the Mease 24row ,cas v4r and Mark Jackson double core have been in the high 9s many years ago.

 

[TTipe]

Red

Red Armstrong makes 1000hp on a slic without alky and doesn't see that kind of intake charge temps vs ambient.

How many folks in the "Time Slip & Combo" section run 10's or better on Front Mounts vs slics? Let the data speak for itself.

 

[TTipe]

save your $ then a stock location intercooler can make a ton of power.now if you are going to put together a pure pump gas combo a huge front mount will allow you to push the tune a little more.

By your own admission the tune can be pushed further with a front mount. The original question referenced a street car which by your own admission will benefit. A PTE SLIC is $1k (which I just sold) and so was my RJC 315 xtf. If you are so inclined to pay $2k for a Fairpark than more power to you. Please remember the PTE has a 1.5 psi pressure drop vs the RJC 315xtf with about 0.7 psi pressure drop. The ambient to output temp delta is 40 to 50 deg F vs 20 degF. The laws of physics prevail.

 

[blklt1z28]

My car runs consistent high 10's with a pte slic. Stock heads, stock cam and other than valve springs and a TC a stock motor. The thing is massive compared to the stock IC, width, length, height, and thickness. I've hot lapped my car and lost less than a .10 in the 1/4. For what the OP is doing I think it will be more than enough. Not worth the extra work installing a front mount plus the chance of the car running warmer in case his cooling system isn't up to snuff.

I will say that my PTE SLIC will be for sale soon though as I'm going with an LS swap.

 

[Mr.Spool]

By your own admission the tune can be pushed further with a front mount.

only on pump gas

 

[Mr.Spool]

How many folks in the "Time Slip & Combo" section run 10's or better on Front Mounts vs slics? Let the data speak for itself.

not nearly as many that have 11/12 sec cars that run front mounts,xfi,70mm turbo's,aluminum heads,loose converters,twin intake pumps,3.5 -5inch downpipesmy point is that a slic isn't keeping people from running 10 or 9sec.

 

[Mr.Spool]

Correct, and the Mease 24row ,cas v4r and Mark Jackson double core have been in the high 9s many years ago.

those are good intercoolers too.

 

[deezdad]

I'm all for the simplicity of a front mount but a couple things in the "con" column are you are adding more weight to the car at the least desired location, and I've read where many have had surging/lag issues with smaller turbos stock-49-44-60 etc.

 

[0-60n4]

The conversion is complete. I was very happy with the quality and customer service from RJC Racing on the 315-XTR. The fit was good and the installation was easy. Of course I did some extra stuff while I as at it. I wanted to do some painting on the front header panel and grille so I proceeded to remove those parts and the bumper which does make the IC installation even easier for a one person job. Now I just need the rain to stop so I can take it out for a test dive then "tweak'" the tune. From what I have read, I should be able to add 2-3 psi boost and some additional timing??? Boost first then timing???

One thing I noticed: The IC is huge! In a nice way, huge. The second thing I noticed was approximately 25% of the lower portion of the IC has the direct air flow blocked by the bumper. So I decided to do some modifications to increase the direct air flow to the IC and the radiator. I cut a window in the front bumper where the license tag would go and installed a mini grille over the new opening. I've ordered two more of the mini grilles (West Maine) that are 1/2 the width and will add those to the left and right of this one. I also fabricated an aluminum air scoop to direct more air into the IC and radiator area. For now I left it bare aluminum but I'm leaning towards painting it mat black. I just seems to sand out a little much. Agree?

 

[toofastforyou]

I went with a front mount intercooler back in 1998 because i wanted to have it outside of the hot engine bay so that it could take advantage of the cooler outside air and perform at it's best.
If you can afford it put it outside the hot engine bay,and like already said it will clean up the area and give you some more room to work if needed.

X2 exactly. Also a front-mount intercooler is one of the improvements that will give you the most "bang-for-your buck".

Claude.

 

[T- Type Tim]

I'm sure you are happy with the stock inter cooler out of the way under the hood as well

 

[0-60n4]

Here's a follow up with a couple more picture after completing the Longwith front bumper modification. Please excuse the dust on the car. I have fiberglass bumpers so cutting the openings created lost of dust. Obviously the modification is easier on a fiberglass bumper vs. a steel bumper.

With the openings cut, you can see the FMIC directly behind the openings.. This modification has to improve the efficiency of the IC and the radiator. The bumper blocks a lot of direct air flow. I'm actually surprised someone had not already offered a fiberglass bumper with vents in it just for this reason.

 

[Pronto]

Good idea. I would have used mesh to allow maximum air flow though.

 

[Mr.Spool]

I should be able to add 2-3 psi boost and some additional timing??? Boost first then timing???

you may not be able to run both. You will make more power with boost so I would start adding boost and at the same time drop a couple of degrees of timing you can always add timing back in later once you hit a boost number you are comfortable with.if I were you I would monitor intake air temps.