Magnus of Forrester Manifod?

[98TsiAWD]

Ick, you just turned me off from the FRH. I think Ill get the magnus, glad I didnt buy an FRH last week..

 

[xinfiniter]

You've just got to go with the magnus...its just sexy!!

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I am in the process of installing now...I got all the nitrous and fuel lines ran and am waiting for some mandrel bent tubing from summit for my intercooler. Once its here, it should only take another day to install and off to the dyno I go. I will post up the before and after dyno sheets.

p.s. I love my g/f!!

 

[Skeletor]

Either is a good choice. I had the FRH on my car and I loved it. The car drove awesome on the street and I had great transient boost response with my FP Red. I always lifted to shift and transient response was a complete non-issue.

Couldn't go wrong with either if you ask me.

 

[Rick@AP]

Originally posted by DSMJim
I just found this write up on the Forester manifold on the net..

http://www.jakelatham.com/1gDSM/projects/forrester_manifold/index.shtml

Check out what he says at the end:

Sounds to me that this person didn't match up the parts very well on this car. A manifold should be one of the last mods in my opinion.

I've never heard of anyone complaing about the FRH manifold before and I think the results would have been the same whether it was a FRH manifold or a Magnus. But as someone else said, why would you put an aftermarket intake on a autocross car? If they were looking for low end torque then they probably would have been better off with a stock manifold.

 

[greathuskie]

98, dont buy the magnus based on that website, look into it a bit more, kilurv8s car has done wonders with the FRH manifold and didnt lose much if any torque down low, there is dyno slips at www.forresterracingheads.com

 

[eclipsefwd]

I just saw that guys website that said he lost all kinds of torque and had more lag. That kinda scares me cause I am getting ready to purchase a FRH mani. Does anybody else have any first hand experience with the FRH manifold? How is non boost performance? How is transient boost response? Any more lag after the manifold? Thanks guys.
Ryan

 

[talonted_one]

I have talked to a VERY RELIABLE source that on the flow bench, the magnus manifold only flowed 4% more than an extrude honed 1G intake manifold.

Is this true? If so why are people singing such praises about this manifold? Is the design that good that you don't need to flow alot more air???

just bought a magnus and with this info I am wondering why should I keep it.

Does anyone know anything about the BJ's manifold for a 2G?

 

[Rick@AP]

Believe none of what you hear, and half of what you see.

 

[kilurv8]

Wow, this is the first complaint I have ever read about the FRH intake manifold. I LOVE IT. I have had it on my car longer than anyone because I have the protype model. I first ran my 60 trim on a 1G manifold and I could really feel it being bogged down up top. I installed the FRH at Dale's shop so we could check fitament before he put the order to the foundry.

I noticed zero around town and off throttle loss and my logs even showed that the car came onto boost faster for around town driving as well as after shifts at the strip.

Keep in mind that the FRH might have shorter runners Just over 4 inches compared to the 9 inch stock ones but mangus runners are not much longer. The big thing that I liked about the FRH was that the runners have huge radiused entrances which disrupts airflow much less than hard 90 degree entrances. Also they start very large and shrink down gradually to the head ports thus acting like velocity stacks which speeds up the air as it enters the head. Hell, Dale put it on his bone stock 1990 before we put it on my car to show that it didn't lose performance or affect how a car would drive. AMS ran the manifold on their Evo 3 race car and went high 9s on the brakes. So it seems to me like it preforms well in both avenues.

Some people steer away from Dales manifold because it is different than what DSM guys have been used to but DSMs cant get companies like eddlebrock to make manifolds like they do for the hondas. Personally, after holding the FRH and the Magnus, I prefer the FRH.

I am speaking from a biased stand point as I am good friends with Dale, not to mention that my brother and I convinced him to move forward with the manufacturing of the manifolds. But i simply prefer the FRH.

The dyno plots are WOT plots but they do give you low rpm off boost results also. The FRH matches the stock intake manifold off/low boost almost exactly so I am not understanding how off boost can suffer so much. Dale knows cylinder heads more than any person I know and he built the manifold plenum to hold the proper amount of air that a motor our size should have.

Take my opinion as you wish, but I saw a whole lot of benefits to the FRH over the magnus and that is why I prefer it. Like I said, this is the first negative account I have heard of the FRH and I am rather suprised.

 

[kilurv8]

I also forgot to mention that the phonelic spacer keeps the manifold cooler and should result in somewhat cooler air charge which should equate to a denser intake charge. This is theory but I do know that the manifold is a lot cooler than my 1G one was.

 

[tanner261]

Flow numbers do not represent dynamic flow. A small gain on a flow bench is nothing compared to the resonant tuning effect from a shorter runner. You will lose bottom end by going to a shorter and/or larger cross sectional area runner. Runner length and cross sectional area are what determine the RPM at which peak power occurs. Plenum size has very little effect on what RPM your peak power will occur, but has great effect on throttle response and how much power is produced.

You can see huge gains over 6.5k RPM with most any aftermarket manifold made for a DSM (FRH, Magnus, BJs, Buschur, Venom, etc.). You will not lose as much bottom end power while at full boost, as represented by the FRH dyno graph, but as JakeL says, off boost power suffers. This may only be seen with smaller turbos as the effects are seen below 4k RPM. Everyone running something 50 trim and larger may not notice the loss in bottom end because the turbo doesn't spool until after 3.5k RPM anyways. i.e., you don't have power below 3.5k RPM with a larger turbo. And as stated before, when you are racing you should downshift, so you are above 4k RPM anyways.

If you want a drag car, or a faster daily driver, an aftermarket intake is a good choice to make more power. There is more area under the curve to be had in the higher RPMs. I'd recommend staying away from them if you autocross your car; on the other hand, if you road race your car it would be a good upgrade because you should have more asphalt to be in the right gear. The Magnus manifold should give better transient boost response because of the smaller plenum volume and longer runners. The FRH manifold will make power to a higher RPM, which isn't really a good thing as a DSM transmission doesn't always like to shift at 9k RPM. I think the Magnus intake is better suited to a daily driver than the FRH. Based on the FRH dyno graph, the manifold makes power until the car is shut off at 140mph. I'm not sure what RPM that is on that car, but I'm lead to believe that manifold is tuned for too high a RPM and isn't taking advantage of the car's useable RPM range. I haven't seen a FRH dyno graph with RPM on the x-axis. Looking at Magnus dyno graphs, the power peaks at 8k RPM http://www.e-smithey.com/pic/dyno1.gif Just right for a DSM.

I was seriously considering a Magnus or FRH manifold for my 16G powered car, but I decided autocross is too much fun to sacrifice low end power. I have a cyclone manifold sitting in the garage that will be bolted on when I have the time. May even dyno the car with the butterflies open and closed to see if the low end gain is worth the effort.

Does anyone have a back to back comparison of the 16G powered car AMS dynoed with the stock vs. FRH manifold? Their website hasn't been updated for quite some time with the manifold dyno.

 

[talonted_one]

Hey thanx for the informative post

 

[Rick@AP]

I believe that tanner261 made some good points, however, I think when you are looking at the dyno plot that is given for the FRH manifold tells a lot more than what most people realize. The dyno shows that the manifold did not loose but gained HP everywhere, even at low speed. This is important to those that want to have a fast daily driver without the normal shift of power to the upper rpm range that is normally associated with an aftermarket manifold.

To really tell the full tale of the differences between the manifolds we would have to plot transient response times between the manifolds on the same car. This is where I believe that the FRH manifold may suffer.

 

[tanner261]

Rick@AP, are you looking at the graph at forresterracingheads.com? There are losses below 6.5k RPM, not huge, but you can't say that the manifold picked up HP everywhere. We need that dyno graph to display RPM. I know that 114 mph on that graph is near 6.5k RPM, is the car FWD or AWD? I'm assuming the dyno was done in 4th gear.

These dyno plots should also include boost pressure to really compare HP numbers, along with RPM.

 

[Rick@AP]

OOPS, You are right . I was going off my memory of the dyno plot. There were some very small loss in the plot.

 

[eclipsegsx9797]

hey i have been doing alot of reasearch on both of these manifolds for while now because im looking to get one, ams sells both of them and loves the power they put out first of all. second with the magnus i know you wil gain alot of hp in the upper rpm's and loss alot of tq, but if you get it tuned right you will spread all that hp out accross the rpm's and even build some more tq, ill try and find the graph i seen on this. as for the forrester i havent looked into it as much as the magnus but from what i have read that its good.

 

[Cazzo Gigante]

Tevenor runs a Magnus intake in his autocross car with excellent results ask him how he likes it. The Magnus intake is also used succesfully in many Roadrace cars all over the world. Some people have reported as much as 75 hp gains by a simple swap. Most are in the neighborhood of 40 - 50 hp increase.

These guys have built tested and dynoed over a dozen different intake manifold designs before they came up with what they are selling now which will by no means be its final incarnation. (remember the two piece intake? trick for making quick switches on the dyno) As to the velocity stacks in the intake, and why they are shaped the way they are? Proven to make more hp that way instead of a rounded drop, laminar airflow and a boundary layer created by the turbulence of the raised stack help create a venturi effect over the stack. Plenum volume was calculated to not lose hp up to 9500 rpm and retain transient boost response of the original intake manifold. Nobody has done more actual hands on research in plenum design, runner length, and flat out research on intake manifolds for the DSM than Magnus.


Magnus runs the same intake off the shelf on their race car to prove that it works. The car has gone 153mph WITHOUT nitrous. Who else has done that? Thought so.

 

[LILGSX96]

and chicks dig it!

 

[BAD-TSi]

Hey nolv4v8, is this GSX of yours black?? You just might know me.

Anyway, my plan is to run the FRH intake, the guys at AMS seem to love it, and I'm impressed by its design. But this has prooved to be an informative argument.

 

[Guerillah]

whats the inside diameter of the runners on the magnus intake and forrestor?

 

[TRBOTSI]

I have the FRH but if I were to do it all over gaain, I'd get the BJ's. I think the Magnus has a lot of numbers behind it because of the amount of people running one, in comparison to the others running FRH, BJ's, etc

 

[tanner261]

Originally posted by Guerillah
whats the inside diameter of the runners on the magnus intake and forrestor?

Can't say what the runner diameter is on either manifold, and you would have to specify a location to get a diameter measurement as the runners are tapered. I will say the taper on the FRH manifold's runners is way too much, a smaller taper is preferred.

Yes, velocity stacks are better than a radiused entry into a runner, look at a manifold from a Ferrari 360, or the new Carerra GT.

I'd like to hear Tevenor's comments on the Magnus manifold vs. stock for autocross use.

 

[Mike 99GSX]

Originally posted by Cazzo Gigante


Magnus runs the same intake off the shelf on their race car to prove that it works. The car has gone 153mph WITHOUT nitrous. Who else has done that? Thought so.

Buschur, long before Magnus

 

[Tevenor]

The magnus intake manifold gave me wood the first day I saw it. It gave me more wood the first time I ran it up to 8k and the car kept pulling like it wanted to go to 9. Be the king. By the Magnus intake.

Now on to actual numbers.

Running an L1R turbo from AGP (Which fucking rocks by the way!), I recorded a 2-3lb per minute increase in air flow from 4000 to 6500 as compared to a ported 2G intake manifold setup with a 2G head (36lb/min at 20psi to 38-39lb/min at the same boost pressure). 6500 was insane. While the stock 2G manifold caused air flow to plateau over this rpm range, with the Magnus intake, air flow continued to rise linearly
through 8k.

This all on a 6-bolt 9:1 compression Magnus block running my stock 2g head with 1G STOCK cams small Griffen FMIC and my fucking kickass turbo.

The L1R on the original setup as described above hit boost threshold at 2500 and full boost of 20-21 psi by 3000. After the install of the Magnus intake, boost threshold moved up to about 2600, spool time took about 100 to 200 rpm longer so full boost hit about 3200-3300. Transient response is absolutely unfucking believable. I am talking <500 rpm from full boost-no boost-full boost. The external dump never shuts up.

As some of you may know, my focus is autocrossing. So naturally I was as skeptical as most of you about ANY sheet metal intake. After having a chat with marco, he convinced me to try it and I don't regret it a minute. It did require a slight tweak to my driving style. Dealing with small fast spooling turbos but no top end had trained me to early shift and stay low throttle positions. Now that I can continue to pull on the high end, I actually have more range in a single gear. For instance, normally a semi straight power pull in 2nd I would shift up to 3rd if I reached over 6000. Why? Power loss and more stability for off throttle application of brake. Why be up there if it didn't get me anywhere? Now 2nd gear runs and pulls up to 7500 so I end up in a higher rpm range which will unsettle a car in a brake-turn situation. I had to adjust my driving style accordlingly. Once I did, being able to focus on the course for a longer gear helps greatly in the smaller regional races. The extra power helps in some of the bigger scale races. It's a win win.

But be wary of one thing. The minute you install this thing and see the top end increase, if you don't already have cams, you will be wanting them. I will be getting mine soon. Yes I still plan on autocrossing. Who says an autcross car can't go 11's? It's already gone mid 12's at 112 on pump.

To sum up: The Magnus SMI focking rocks! It made my L1R sing over 6500 RPM. Buy it.

 

[wkd4g63]

ive got the bj's part and LOVE it ! i didnt notice any difference in lag, and id have to say hes one of the pioneers of the sm intake for the dsms! the quality CANNOT be beat, often imitated but never duplicated!


JP