Budget Intake Manifold/TB Options

[dsm-onster]

Shifting from 1st at 7000rpm to 2nd will put you at 5500+ rpms in 2nd. Al the other shifts will be similar. Who cares about power at 4500rpms? If you're going to race, race!!! Unless you one of those guys who likes to repetedly punch and let off the throttle in 5th gear on route 13. If that's the case, you should have bought a 396 chevelle SS. . . I which case, I'd still take your title in a heads up race.

The big h1c flows about as much as the 50-trim, so you would benefit from better high rpm VE; whether your turbo does spool to full boost by 3500rpms or not. As you mentioned, you will have more power down low than other SMIM setups no matter what, because your turbo spools faster than the typical 'SMIM-worthy' turbo. But as I mentioned before, the mitsu engineers weren't morons; they built the transmission so that you would shift back into the powerband when you upshift at close to redline. No one complains too much about dsm tranny gearing.

I vote for a 1g head/manifold swap. Or a smim. NO ONE, zero, nill, complain about losing low end power when swapping from the 2g head/intake to the 1g head/intake. The 1g head DOES have larger ports, and the 1g intake DOES have slightly shorter runners with a significantly larger plenum.

 

[deflator]

I vote for a 1g head/manifold swap. Or a smim. NO ONE, zero, nill, complain about losing low end power when swapping from the 2g head/intake to the 1g head/intake. The 1g head DOES have larger ports, and the 1g intake DOES have slightly shorter runners with a significantly larger plenum.

Even a used SMIM is too much for the budget I have left for this car. I would swap to a 1g head, but I've already polished and portmatched my head and had it refreshed at the machine shop so I didn't want to sell it.

 

[Boosted98gsx]

Even a used SMIM is too much for the budget I have left for this car. I would swap to a 1g head, but I've already polished and portmatched my head and had it refreshed at the machine shop so I didn't want to sell it.

You could very easily recoup the investment of a 1g head through selling that 2g head of yours. There are people who are desperate for 2g heads out there. If you want high end flow, you opt for a 1g head. A 2g head is more of a "road course" head, not a drag head.

The 2g head will get you higher torque lower in the rpms, but will choke off up top compared to a 1g head, stock for stock portwork.

If you're building a dragster 2.0L get a 1g head. If you're building a street / strip 2.3 (like myself) get a 1g head. If you're building a street/road 2.0L, use a 2g head, where you need the torque.

Since you have the head off the car, my vote is switch to a 1g head, and get an extrude honed 1g manifold. All can be done for less than the cost of a SMIM if you shop properly.

 

[deflator]

Since you have the head off the car, my vote is switch to a 1g head, and get an extrude honed 1g manifold. All can be done for less than the cost of a SMIM if you shop properly.

Interesting, I wouldn't know how much to sell my refreshed 2g head for though. The machine shop bill was $240. Then I'd have to get the new 1g head refreshed. And I would have to get different ARP headstuds too wouldn't I?. The headgasket is the same for all years at least right?

 

[Boosted98gsx]

A newly rebuilt head should sell for $350-400

ARP's are block dependent (thread pitch) not head dependent, and headgasket is based on bore size, again, determined by your block

 

[deflator]

But would this really be worth all the trouble over a 2g head with an RVR manifold? I'll have to sell my head and the manifold I just bought then buy a 1g head and get it rebuilt. What kind of gains do people see from 1g head swaps?

 

[pboglio]

You already have the EVOIII intake manifold, just run it. In combination with an FP exhaust manifold my peak power curve shifted from 6000 rpms to about 6500 rpms and at 7000 rpms my power is up substantially.

 

[VETTE_50_TH]

If it were me, i would just have saved my money and bought a SMIM. The minimal gains you get out of a EVO III manifold isnt worth it when compared to the JMF or Magnus SMIM. Since you already got a RVR, get a 1G TB and port that sumbitch.

About the 1G head, if you are even thinking about doing that, just buy a longblock from a 90-91 and rebuild the whole thing. That would be a better choice, becuase then you get the stronger block and better flowing head. I think a few posts down a guy talks about a 2G is better for low end torque and 1G is a drag head; i think you are really going to see separation between one better than the other is when you start adding cams and porting and what not. There probably isnt that much gain going from one to another stock to stock.

James

 

[99redgst]

Shifting from 1st at 7000rpm to 2nd will put you at 5500+ rpms in 2nd. Al the other shifts will be similar. Who cares about power at 4500rpms? If you're going to race, race!!!

This is obviously coming from a drag racer. I completely disagree with your logic. There are many situations on a road course or autox where you will be below 4500. Usually downshifting for 1k usable rpm before having to upshift isn't worth the time as opposed to just staying in the same gear.

As far as 1g head vs. 2g bigger ports doesn't necessarily mean its better. The 2g has better port velocity and a straighter path at the valves. I'm not going to say one is better than the other because it comes down to the application it will be used on.

Not everyone is concerned with peak power, which it seems most people in this thread seem to think so. To the OP I say keep the Evo 3 mani, unless all you care about is straight line performance and getting the best timeslip you can.

 

[dsm-onster]

My logic may be based around a drag race. And you may disagree with it, but I hope the OP isn't planning on drifting on the street. I hope isn't drag racing on the street either. But he's not mentioned his goal. He DOES have fp2 cams, to give you an idea of his setup. You're opinion on where the power band should be makes very good sense for such a purpose built car.

NO ONE has ever lost throttle response and/or low rpm torque from swapping to a 1g head intake manifold. . . But the ports ARE bigger. The Plenum IS larger. And the stock 1g intake manifold DOES flow more than a SMIM up to 6500rpms. That was proven. . . I'm not understanding why a budget-minded build would not include such a modification. You're giveing advice on speculation: because narrow runners make more torque at lower rpms. It's not speculation when everyone who's done the swap has no issues with torque at 4K or has mentioned the car pulls less at the low end. Where is there proof in a loss in low end torque from doing the swap? I'm giving advice based on speculation, as well. It may be speculation that you gain power up top, but being that the plenum IS larger and the runners ARE shorter, we have the model of the SMIM on which to base this speculation. There is no noticable loss in low end based on the reviews of said swap, and it is logical to assume there would be gains up top.

In my experience any upgrade to a larger area throttlebody will net a snappier throttle response. The 1g head/intake combo allows that to be done easily, plus provides a larger plenum.

A 'street version' SMIM does very little to take low end torque away, as been verified by many reviews. Contrary to popular belief, a larger plenum helps LOW END.

If a boost is desired in a higher rpm range, closer 7000-7500 rpm, the plenum will need to be 10-15% smaller. To get a boost in the 2500-3500 rpm range, it will need to need about 30% larger. The plenum size of a Helmholtz resonator may go
against the typical plenum size rules, but the rules change when the resonator is being used. The whole Idea of a plenum is to allow the gases to slow down and gain density. The Helmholtz plenum makes a dense charge by use of pressure waves, in the same way tuned port intake runners work.​

For the reference to this, see link in the next few sentences. So off-idle/pre-boost response will be better. The runners are shorter, but wider. More width helps lowend and less length hurts lowend. Using Helmholtz math (which takes into consideration diameter and length), the stock 1g intake manifold hits the 3rd harmonic with 272s/fp2s at about 4k, which the op is using. Interestingly, this is the same harmonic that is achieved at 6500rpms with the stock cams and the stock 1g, based on helmhotz theory. And further, with 272s/fp2s, there is a 2nd harmonic displayed with the stock 1g intake manifold at around 7K.

You could very easily recoup the investment of a 1g head through selling that 2g head of yours. There are people who are desperate for 2g heads out there. If you want high end flow, you opt for a 1g head. A 2g head is more of a "road course" head, not a drag head.

The 2g head will get you higher torque lower in the rpms, but will choke off up top compared to a 1g head, stock for stock portwork.

If you're building a dragster 2.0L get a 1g head. If you're building a street / strip 2.3 (like myself) get a 1g head. If you're building a street/road 2.0L, use a 2g head, where you need the torque.

Since you have the head off the car, my vote is switch to a 1g head, and get an extrude honed 1g manifold. All can be done for less than the cost of a SMIM if you shop properly.

This would be nice. . .

 

[99redgst]

You're giveing advice on speculation. It's not speculation when everyone who's done the swap has no issues with torque at 4K or has mentioned the car pulls less at the low end. Where is there proof in a loss in low end torque from doing the swap? It may be speculation that you gain power up top, but being that the plenum IS larger and the runners ARE shorter, you have the model of the SMIM on which to base this speculation.

My logic may be based around a drag race. And you may disagree with it, but I hope the OP isn't planning on drifting on the street. I hope isn't drag racing on the street either. But he's not mentioned his goal.

Not sure where I was "speculating"? Unless your referring to us not know what his intents for the car are. The reason for my advice is it sounds like the OP doesn't want/have much money to throw into the project. He already has the 2g head and evo intake, is he really going to notice a difference going to a 1g setup?

Just to clarify, you want proof that there is a low end loss, but as far as the upper end goes you are fine speculating that the 1g out performs by looking at it? Seems a little contradictory to me.

I would really like to see dyno results between 1g and 2g with nothing else changed on the setup. I never have, for you to say that NO ONE has EVER lost any low end who imply that you have talked to every single person that has done it and they all have dyno graphs to prove it. Its a pretty bold statement if you ask me. I think a better statement would be "No one I talked to has noticed a difference in the lower end of the powerband between the two".

One final thing I would like to point out is that the EVO 3 runners are shorter than a 1g intake, so given you speculations would that not make it a better choice?

 

[dsm-onster]

I agree, that the evo intake is better. Anything is better than the 2g intake , except perhaps trying to put a 1g intake on a 2g head. This is what I'm trying to say.

Helmholtz resonance is not speculation. There are specific rules that the 1g manifold follows for it to flow better. I agree. I should have clarified my conclusions better.

 

[Black_Bullet]

True. But while you may not notice the loss of lowend, the fact remains that the loss is still there. Each application will be different, but any dyno will show the loss of power in the lower RPMs.

http://www.magnusmotorsports.com/images/evo_oem_vs_cast.jpg
http://www.magnusmotorsports.com/images/evo3037_oem_vs_cast.jpg

I agree that the EVOIII IM is a good choice for a budget street car and the gains are probably comprable to that of the Extrude Hone process I mentioned before. The EVOIII IM would also net lower loses in the lowend than an aftermarket cast or SMIM. It also has that benifit of being cheaper, albiet harder to find.

I wont go into specifics, but being that theres a cheaper, AND proven better SMIM out there, I dont think a dyno graph from a magnus is at all helping the case of encouraging someone to run a SMIM.

For the OP, people have emphasized the differences in different intake manis/heads and which is better for what application, but honestly none of that matters. In your case, I think its simple, you've state you are on a budget. Anyone on a budget cant expect to get there cake and eat it to, and will have to make a compromise between price and performance, and in that case you've already made your decision, you got the EVO3 intake manifold, if it bolts up to the 2g head, then bolt the bi*** up, go snag a 1g N/T throttle body out the junkyard, slap new turbo shaft seals in it and put your car together and dont worry about little details in which head would be better for you and just go with what you already have, save money, and go on about your way...

Problem solved.

 

[deflator]

My logic may be based around a drag race. And you may disagree with it, but I hope the OP isn't planning on drifting on the street. I hope isn't drag racing on the street either. But he's not mentioned his goal. He DOES have fp2 cams, to give you an idea of his setup. You're opinion on where the power band should be makes very good sense for such a purpose built car.

NO ONE has ever lost throttle response and/or low rpm torque from swapping to a 1g head intake manifold. . . But the ports ARE bigger. The Plenum IS larger. And the stock 1g intake manifold DOES flow more than a SMIM up to 6500rpms. That was proven. . . I'm not understanding why a budget-minded build would not include such a modification.

My eventual goal for the car is high 11's with nice street manners with the automatic. You've got me torn here now, unloading and replacing the parts with 1g parts would be a good amount of work and I am currently recovering from illness. I wish I had known about the airflow gains from a 1g head sooner.

I'll probably have to go with the 2g head and RVR mani for convenience, but for the original purpose of this thread, a 1g head/mani swap seems the best for your buck. I was reading stuff like 40hp gains from it.

 

[Black_Bullet]

My eventual goal for the car is high 11's with nice street manners with the automatic. You've got me torn here now, unloading and replacing the parts with 1g parts would be a good amount of work and I am currently recovering from illness. I wish I had known about the airflow gains from a 1g head sooner.

I'll probably have to go with the 2g head and RVR mani for convenience, but for the original purpose of this thread, a 1g head/mani swap seems the best for your buck. I was reading stuff like 40hp gains from it.

High 11s and you are planning to run a H1c.
You can achieve that with either heads, and I think you made a fine choice with the Evo intake mani. Even if you would get gains from the 1g head, you are on a budget and that means your not building the perfect car, Just leave your 2g head for convenience and save your money as stated.

 

[99redgst]

There are specific rules that the 1g manifold follows for it to flow better.

I agree with this. Larger plenum, shorter runners, traits of higher flowing manifolds.

Have you ever had an evo 3 in your hands?

The runners are about 8 1/2-9 inches long. The runners have alot of taper to them, inside the plenum the opening is about 2 1/2 inches that tapers down to the 1 inch tall head port. Things you would find on those high power SMIM. The plenum is smaller however, although looking inside it looks like it flows good for its size(This is purely my speculation here though). Seems as though this is a better designed intake than the 1g, so if the head differences are negligible, I would have to say the evo 3 is the better choice.

Here are some shots of the inside of the plenum:

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[JayRolla]

I agree with bullit. I had to compromise when I was on a budget. Either I could get dsmlink or just buy a maf-t and 1200cc injectors for cheaper than an eprom and dsmlink so I could run e85. I bought the maf-t/safc and injectors to run e85 and happier than ever. Yes its not the best way but it works.

Just like you, the setup will be better than stock but not the best. Money always comes into play when modifing cars. Thats what sets us from the big guys.

 

[dsm-onster]

High 11s can be done with the stock 2g stuff probably. But I agree, you've done a good thing with getting an evo manifold. I was never argueing that. Sorry to mislead you. That was not my intention. You have picked a manifold that:

1) matches your head runners, of which are big enough for your goal;
2) has tapered runners;
3) allows a larger throttlebody to be installed easily, wich has been known to increase throttle response.

Cheap and easy. You will notice that at WOT, suddenly, the plenum volume includes the entire IC pipe after the IC, if there's not too much change in diameter along it. This is because the plenum diameter equals the throttle body diameter. The air doesn't 'know' that theres a throttlebody at WOT separating the plenum from the ic pipes. One reason why I wanted to get rid of the 1g tb elbow. I had to reduce from 2.5" ic piping to the size of the tiny TB elbow inlet. Then the elbow expands to the size of the tb bore. This encourages the air to see only the volume after the elbow as the plenum. Switching to the n/t tb allowed me to only increase the diameter slightly from 2.5" ic pipes to the tb bore. MY take on it is that you can go small to big or big to small and the air sees the entire volume as still one plenum, but if you go big to small to big then where the small point is is where the air will be encouraged to 'think' the plenum begins.

 

[99redgst]

You will notice that at WOT, suddenly, the plenum volume includes the entire IC pipe after the IC, if there's not too much change in diameter along it.

Wow, good point. Never really thought of that.

 

[pboglio]

Anybody with any before and after results swapping to a 1g head/intake manifold on a 2g?
I've heard gains from some people and no gains from others.

 

[Boosted98gsx]

Anybody with any before and after results swapping to a 1g head/intake manifold on a 2g?
I've heard gains from some people and no gains from others.

Completely depends on the tuning, and unless you can garuntee it's equal among all the different cars that swapped, no way in hell you're going to get a definite answer.

I swapped to a 1g head because at the time the rage was the larger ports, while I would have been better off sticking with the 2g head on the 16g. Now that I am on the 35R and stroker, I am very glad I swapped over.

 

[dsm-onster]

Wow! I wish there were. No one will anty up and do a simple test. I can't I don't have the time. I'm too busy proving the morons on the evom forum wrong about twin scroll turbine housings, and literally making a big h1c compressor map with my setup since none can be produced.

 

[Boosted98gsx]

Wow! I wish there were. No one will anty up and do a simple test. I can't I don't have the time. I'm too busy proving the morons on the evom forum wrong about twin scroll turbine housings, and literally making a big h1c compressor map with my setup since none can be produced.

It's not as simple nor cheap as you might think. There are too many fluid dynamic tests that would need to be done, and renting of a CNC that can needle plot the ports between the heads, as well as the manifolds. However, using fluids as a basis for analysis, one can determine that the 1g will flow more higher in the RPM band due to the simple fact there is more volume in the runners leading into the combustion chamber for larger turbos to flow more. The 2g however, with the longer narrow runners will maintain velocity into the head better in the lower rpms, and choke off in comparison to the 1g. It's completely dependant on what you want to do with the engine; whether it be an area under the curve street car, or a massive power, high revving engine for a straight line dragster.

 

[99redgst]

What about using a flow bench? Would that give any useful data? Could be done with the heads separately then with the intake manifolds bolted on. A lot less variables but I don't know if flow bench data would be as helpful as dyno runs.

 

[dsm-onster]

It's not as simple nor cheap as you might think. There are too many fluid dynamic tests that would need to be done, and renting of a CNC that can needle plot the ports between the heads, as well as the manifolds. However, using fluids as a basis for analysis, one can determine that the 1g will flow more higher in the RPM band due to the simple fact there is more volume in the runners leading into the combustion chamber for larger turbos to flow more. The 2g however, with the longer narrow runners will maintain velocity into the head better in the lower rpms, and choke off in comparison to the 1g. It's completely dependant on what you want to do with the engine; whether it be an area under the curve street car, or a massive power, high revving engine for a straight line dragster.

What? run to redline with dsmlink with a common cam upgrade or stock cams. The recording of the lb/min curve will suffice. A swap between a SMIM and a stock manifold would be a nice additional test.

I'm not talking about test bench racing (. . . bench racing). I'm talking about how does helmholtz resonance (which cannot be measured with any device you're discussing) and a real world situation will be affected by the swap. If the manifold/head combo does better lower in the rev range, then it will show. No matter the turbo.