I need to know if this is a good set up and if I should modify it in anyway!!!! I am building my topend and I was wondering if the bottom end will be safe, considering I have great compression and everything appears to be good to go. Just tell me what you think, as far as my limitations in hp and engine safety with leaving the 7 bolt bottom end alone.

My Head: Manley 1mm over valves, Topline rocker arms, Revised "no tick" lifters, SI Dual springs w/Manley Tit Retainers, SBI bronze valve guides, Crower stage II cams, Cometic HP metal HG, ARP head studs.

Deciding on wether or not to have the head ported, give me your opinion on this?

Or should I just match the openings on both of the mani's to the openings to the head?

thks

De ja vu. http://www.dsmtuners.com/forums/showthread.php?t=188803

ECLIPSE4x4 said:

originally posted by:
Moderator

Wow Ricekiller... you managed to post in both and have nothing helpful to say in either.
Possible a double post by mistake. Give the man a break.

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I not giving him a hard time just goofing around. Sorry!

boostyGST said:

Deciding on wether or not to have the head ported, give me your opinion on this?

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Dont. Its a waste of money, especially in a fwd car. Your "spin" your money all the way down the track anyhow.

boostyGST said:

Or should I just match the openings on both of the mani's to the openings to the head?

thks

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Yep! And maybe polish the intake side and exhaust side a bit.

hey sorry for the repost that was my bad.

thks for your imput, as far as it being urgent, i have my engine apart and the block is sitting in the machine shop and the machinists is getting bitchy........



thks again.
Tyler

Unless your pushing a ton of power their is no need for oversized valves. The stock valves do a great job. I would just go for some cams and new springs and retainers. Oversized valves will help out top end but hurt your bottom end power. On a stock 7 bolt your not going to push enough to warent oversized valves.

well i dont understand, in my little brain I thought it was known that by modifying the head, bigger turbo, injectors and what not will help the performance of my motor, and give me desired HP.

Put it this way, I have 4000 bucks to spend on my car, what should I do!!!

yeah all that will improve the final power numbers at high rpms but you will probably lose low end power. depends on what you want out of your car.

what i am asking i guess is, with 4000 what would you guys do to your engine. Im curious to know cause everything I think of is put down on this site.


Also i want to explain my point of view:

If you take a 4G63 engine, do not touch the displacement, compression, and stroke. However decide to spend money to just beef it up, ie manley rods and ross pistons the HP will not increase, however spend the money to improve upon these things you will have the crazy lowend that everyone is talking about. But with a FWD car is all that bottom end going to be useful? I dont think so .... "spin all day". However if you machine the head and beef up the valvetrain you are going to allow more air into the engine and combined with more fuel and boost this will create more overall power. Telling me that doing this is going to decrease lowend is just bull, considering that any engine you build and you allow more air/fuel into the engine you are going to gain overall HP.

People are telling me dont touch the head its fine, "it will just improve top end", but if my bottom end is in perfect shape and I dont want to spend the money to just put beefy rods and pistons in it, and dont have the crazy cash to have all kinds of machine work done with the price of lets say a stroker kit or oversized pistons. What else can I do to the motor. Considering that these motors are not designed for bottom end anyway, I mean they have a turbo.......,........there is you "TOPEND"

All i am saying is that we are talking 4 cylinder motor here, with the assist of a turbo and like i said, without increasing one of those three factors above, the bottom end will never change, however if more air(bigger turbo and valves)/fuel(FPR/255HP Pump/750or>inj) the net HP is going to increase no matter what.

Tell me what you think.

Ok. Here's my take on this again. I have fwd just like you so let me tell you, it doesn't take a whole lot to make it stupid fast...especially on the long runs.

Building up the bottom end is futile in my opinion because its fwd and wont be able to handle a lot of whp without spinning out anyhow. If you've got a built block and have the supporting mods to have around 350+hp you're going to need a lsd and slicks to keep wheel spin to a minimum (on the track).

On the streets you can pretty much forget about it. You'll smoke your tires clean through 1st - 3rd gears if your clutch is up to par. There are proven 11 second timeslips using the 14b turbo so that tells me that "fast" is about tuning more so than turbo size.

Get your intake and exhaust gutted out. Raise boost and tune air/ fuel. Injectors, fuel pump, fuel computer, etc etc...

By the way. You can beef up the head all day long but are the gains worth the price to do the work? On a fwd you will straight "haul" on the interstate with only an EVOIII turbo (at above 18psi) with supporting mods. You'll run out of gears before your engine runs out of power. And with an upgraded intercooler you'll easily be able to run even higher boost. Dont even get me started on what you could do with intercooler "plus" race gas! Its insane. No traction at all my friend.

So in my opinion unless you are in competition it would be unnecessary to "build" a fwd dsm block that is already capable of 400hp stock.

Hope this helps ya.

Hey I'm no pro engine builder. I do know that the valves already fill up the cylinder head pretty well. When you go even 1mm oversized you will experience a lot of valve shrouding (the valve is actually in the way and creates a restriction) at lower RPMs. This is where you will loose some bottom end. And if you plan to DD this car low end power is where you gas miliage is at. If you want to spend $4K on a Head it's possible. Get a 2G head and have it fully ported with 1 or 2mm oversized valves and extensive bowl work done. It will flow a lot more than a ported 1G head ever will. It's a more efficient intake/exhast angle design. With a high port and moving your injectors to you intake you might be able to see some low end power but then again you are going to end up spending more on your cylinder head work than most people spend on their entire built engine.

With 4K you can do a lot to your car. I would look at the tuners guid and follow it. Or here is my suggestion as I guess I didn't really give much input. Sorry bout that.

1. Exhaust 2.5" DP and 3" DP back will help you not to creep.
2. Fuel System. (Walbaro 255, AFPR, and at least 660 injectors)
3. FMIC (doesn't need to be hugh a street kit will do you fine)
4. Clutch Since you are FWD I would suggest a ACT 2100 to allow a little silppage
5. DSMLink or Chipped EPROM ECU (will save you lots of headaches in tuning w/piggybacks)
6. Evo 3 B16G or maybe a 50 trim
7. Gauges of course

That will use most all your $4K. You will see far better results out of it that way if you don't already have some of these items. Sorry didn't check your profile. For just engine work.

Stage 3 JAM 2G Head
Ross/Eagle Combo
ACL bearings
BSE
HKS 272 combo or FP2's
Cometic HP Head gasket
OEM Mitsu gasket set to assemble the enge
New Front Case
New Mitsu Timing belt, pulleys, and tensioner

That + Machine work will actually probably put you around $4.5K unless you find some good deals on some of the parts. I would just search around and see what is out their and been done. Their are lots of different ways of doing things. I'm pushing about 400-450 WHP right now on a stock bottom end. If taken care of and tuned properly it's not a big deal. I happen to also have 130K on my motor as well.

hey thks for all your imput on this subject, I see tha everyone pretty well as there own opinion on this issue and how to go about doing it, as for now I think I am going to go with leaving the bottom end alone considering the compression is up around 180 on all cylinders and Maglin is producing 400-450hp on his with the same amount of miles mine has....

I just have one more question: Maglin: Go ahead and give me a detailed description of what you have done to your motor and turbo set up, and I will compare to my list of to do's.

thks, Tyler

boostyGST said:

what i am asking i guess is, with 4000 what would you guys do to your engine.

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Daily driver? drag strip? autocross? toy?

Read up on torque vs horsepower. If your turbo spools late in the game, big FMIC, and you have a 1g head with oversized valves, you will not have a "peppy" response.

If you are racing, and top speed is it! then HP is required.

If you are racing with constantly changing speed (enter-exit corners) a torqu-ee response is desired.

Thought much about grammar? I hated English class...but I'll tell you what....it can be difficult to understand some of these notes. A first step is to re-read your post 10 minutes after writing it...before it is posted.

okay

RiceKiller_TSi said:

Yep! And maybe polish the intake side and exhaust side a bit.

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I wouldn't touch the intake side, and polish the exhaust side. I've seen too many cases of people thinking mirror smooth intakes are good, but their engines end up puddling fuel in the intake port.

defrag010 said:

I wouldn't touch the intake side, and polish the exhaust side. I've seen too many cases of people thinking mirror smooth intakes are good, but their engines end up puddling fuel in the intake port.

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How do smooth surfaces puddle fuel in the intake port?

I can see a problem if someone enlarges the port (which inturn reduces air-velocity) and has huge injectors having trouble atomizing fuel ("puddling" at low RPM).

Can anyone explain why smooth surfaces would cause fuel puddling?

they prevent the air/fuel mix from tumbling, which keeps each suspended.

defrag010 said:

they prevent the air/fuel mix from tumbling, which keeps each suspended.

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Is this speculation or from experience? Was there a difference in Reynolds number on the flow bench?

I would expect turbulence/eddys to be a function port velocity, shape, and manifold design. Wall "friction" would increase the boundary layer (lowering the mass flow-rate ).

I have a hard time understanding how port surface smoothness increases tumbling. I have ran air-flow experiments in the GA Lockheed wind tunnel, ran Computational Fluid Dynamics (Star-CD), watched stop-frame video of high-velocity air / fluid interfaces, and written an SAE paper on brake rotor cooling. I am not an expert on fuel injection/intake port design..but rather I am looking to understand the Phyisics.

I'm not sure I believe smooth intake surfaces cause fuel puddling. I may be wrong...but I don't see it.

bjones18 said:

Is this speculation or from experience? Was there a difference in Reynolds number on the flow bench?

I would expect turbulence/eddys to be a function port velocity, shape, and manifold design. Wall "friction" would increase the boundary layer (lowering the mass flow-rate ).

I have a hard time understanding how port surface smoothness increases tumbling. I have ran air-flow experiments in the GA Lockheed wind tunnel, ran Computational Fluid Dynamics (Star-CD), watched stop-frame video of high-velocity air / fluid interfaces, and written an SAE paper on brake rotor cooling. I am not an expert on fuel injection/intake port design..but rather I am looking to understand the Phyisics.

I'm not sure I believe smooth intake surfaces cause fuel puddling. I may be wrong...but I don't see it.

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Welcome to porting. A smooth surface causes it to NOT tumble allowing the fuel to fall out of suspension. This is why when you see a ported head the intake it's ported but not polished to a mirror smooth surface like the exhaust. Then the exhaust side is like a mirror, smooth as a baby's ass.

With the bowls ported and the chambers cleaned up, McKenzie instructed us to swap out our carbide cutter and use one of the cylinder-shaped polishing rolls from our Standard Abrasives porting kit. Polishing not only creates a smooth path to promote airflow, but also resists carbon buildup. The intake bowls are best left >> unpolished because it promotes atomization of the fuel. Minor cutter marks within the intake bowls are enough to keep the intake charge tumbling through the ports and into the cylinders.
http://www.chevyhiperformance.com/techarticles/95518/

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You may want to look at my ride/PM me with some questions. I am only putting down a flatline 320hp right now, but the GT35R will be going in wednesday! Let me know if you need any help/advice from a built FWDer

DSMJim said:

Welcome to porting.....

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Interesting article. Jim, I am somewhat like yourself (from your quotes in other threads). I like to prove things. I do not have the time nor equipment to prove intake surface finish; however, some thoughts on this subject:

1. Stuff that worked in the past, worked for a reason. Whether or not it is fully understood.
2. Surface tumbling is real. (does it help atomize?)
3. Surface tumbling IS the definition of a boundary layer. (small BL increases flow)
4. Atomization is due to a pressure differential (except for a centrifugal bell) accross a nozzle.
5. fluids of different densities do not like to mix (fuel and air in this case)

Does the "fuel-wetting" of the intake surface change, smooth vs rough? If the fuel "wets" a smooth surface more effectively than a rough surface (surface tension of fuel & head material) then fuel may tend to collect. Guaranteed is the fact that fuel-iron surface tension is different than fuel-aluminum surface tension. Fuel additives will also change surface tension.

Surface tension is easy to visualize... a drop of water on a teflon pan (or waxed surface) will bead up (doesn't wet the surface)...high surface tension. WD-40 wets a steel surface = low surface tension. (a little bit of soap or alcohol really changes a liquid's ST).


My bet is on the fuel "wanting to wet" the smooth cast iron surface....think about the next time you paint a car....don't count on your "body panel" to help atomize your paint spray.

i am glad this post has helped you guys out, please feel free to keep up the discussion.

bjones, I'm not familiar with the physics behind the air/fuel mix and flow. However, "puddling" is a coined term that just means poor atomization. The fuel doesn't physically puddle, it just falls out of suspension. Tumbling is what keeps the air and fuel in suspension. I don't think surface tension has much to do with it, because you would be working with minute numbers considering the amount of fuel that is actually in the intake stream.

It might not be 100% "correct" in comparison, but the guy who taught me about porting explained it like the intake port was a river. If the bottom of a river was a perfectly smooth surface, the water would flow in a calm stream down the river with no disturbance. The surface roughness inside the intake port would be like that same river, only with lots of big rocks. Big rocks and a flowing river make foamy, bubbly rapids. It made sense to me if you were trying to mix air/fuel (air/river water).

That's all I got.

I agree 100% with the analogy, but the conclusion may be suspect. Speaking with a fellow builder...most Chevy's are carburated (as the above article states). The pressure differential across a carburator jet is not much...making atomization difficult.

The water stream example is perfect...the foamy-bubbly "boundary layer" slows the flow down at the bottom of the river (in our case a tube)....maximum flow through a tube requires a very small boundary layer (slippery surface). Most of our turbulence (eddys) are generated up-stream (turbo, FMIC, shape changes, TB, plenum to runners. We might not need the rough surface, just really good injectors. Heck, we try to point those injectors right at the back of the valve anyway....not the intake port surface. I think the micro-scratchs are more to increase the surface area (probably double the area of a mirrored surface). Raw fuel (carburated) can coat the port surface, then evaporate: more surface area = faster/more evaporation.

Back to the water stream example.... Inject "dye" into the stream with the intention of coloring the water...you also want max water flow in the stream, and have two choices.

1. drain the dye through a tube into the stream & throw rocks in the stream to disperse.
2. inject the dye under the streams surface @ 1000psi through a nozzle.

option two will more uniformly color the stream, in a shorter distance.

Also, don't discount the surface tension, it is the reason droplets form and how big they are. It has to do with the surface tension between air & fuel (or in the sake of rain...water)

Good topic... I'm not sure the CFM difference amounts to as much as the length of this thread.

Yeah, definitely a good thread.

I see what you're saying, and it makes sense. However, I'm a debater (master'batr ), and I'm going to bring the pressure of the intake stream to the table.
Would the atomization characteristics hold true for both an intake that's under vacuum and one that's under boost?
Let's say our river is now a large pipe that is under pressure. Will the 1000 psi nozzle still have the same atomization effect?

I guess what it really boils down to is the atomization characteristics on engines where the injectors/carb is upstream from the intake ports. Engines like the 4g63 with the injectors in the head would not need to worry about port smoothness in any area except the bowels.