Comp cam choices?

[JONJON]

So I have the mutha thumpr cams but I see the majority of the N/a people here use the xfi 127500 cams. Why did you chose those over the mutha thumprs? Thank you for your answers and I hope this is in the right section.

 

[hamish]

Probably due to the fact they make power.
Not just sound

 

[BruceH]

So I have the mutha thumpr cams but I see the majority of the N/a people here use the xfi 127500 cams. Why did you chose those over the mutha thumprs? Thank you for your answers and I hope this is in the right section.

I'd ask why you chose mutha thumpr cams over 127500? To me that's a bigger riddle than the other way around. I can see not wanting to change springs but once you do the opportunities for higher rpms, boost, and cams are pretty good.

Valve float can kill a motor fairly rapidly. Think of springs as an insurance policy against valve float for higher rpms and boost.

 

[JONJON]

Probably due to the fact they make power.
Not just sound

I had just got the car and like I have said the 3 valve is a new beast to me. I am used to pushrod motors. So I went to a shop I used to go to and they told me to go with the mutha thumprs. I love the way they sound but I did not know anything about the xfi until later. So they always make more power or when I change the valve train and bring up my rpm's will they even out?

 

[BruceH]

So I have the mutha thumpr cams but I see the majority of the N/a people here use the xfi 127500 cams. Why did you chose those over the mutha thumprs? Thank you for your answers and I hope this is in the right section.

I had just got the car and like I have said the 3 valve is a new beast to me. I am used to pushrod motors. So I went to a shop I used to go to and they told me to go with the mutha thumprs. I love the way they sound but I did not know anything about the xfi until later. So they always make more power or when I change the valve train and bring up my rpm's will they even out?

The cams I'm running right now are basically 127500 with a different icl and lsa. The reason I chose them is that the valve events were almost exactly where my previous cams flowed the most air with and without retard. The difference being that these are doing it without vct. It's due to the increased durations. IMO Comp didn't just pick the 500 specs at random.

If the MT are anything like Hot Rods then they should still make a reasonable amount of power with the right tune and long tubes. Stock motors with cai, long tubes, and Hot Rods typically make right around 330rwhp. IMO that's fairly respectable for the mods.

This is just a guess but I'd think the 500 cams would be more driveable than the MT too.

Do you plan on changing anything out or is this just an exploratory thread? If you do I'd suggest springs first if you can't do it all at once.

 

[JONJON]

The cams I'm running right now are basically 127500 with a different icl and lsa. The reason I chose them is that the valve events were almost exactly where my previous cams flowed the most air with and without retard. The difference being that these are doing it without vct. It's due to the increased durations. IMO Comp didn't just pick the 500 specs at random.

If the MT are anything like Hot Rods then they should still make a reasonable amount of power with the right tune and long tubes. Stock motors with cai, long tubes, and Hot Rods typically make right around 330rwhp. IMO that's fairly respectable for the mods.

This is just a guess but I'd think the 500 cams would be more driveable than the MT too.

Do you plan on changing anything out or is this just an exploratory thread? If you do I'd suggest springs first if you can't do it all at once.

Yea the plan is to make the boss block I got into a big bore stroker with some stage 3 rgr heads. I made with those cams and no long tubes or throttle body 334 rwhp. The setup you have is similar to where I am going but with a different head. The compression will be similar but I want to spray with it.The numbers and mods you have are awesome. Thanks for the explanations I appreciate it.

 

[BruceH]

Yea the plan is to make the boss block I got into a big bore stroker with some stage 3 rgr heads. I made with those cams and no long tubes or throttle body 334 rwhp. The setup you have is similar to where I am going but with a different head. The compression will be similar but I want to spray with it.The numbers and mods you have are awesome. Thanks for the explanations I appreciate it.

You are welcome, feel free to ask any questions. I recently picked up some lightened, used, Mahle big bore pistons with a compression height of 1.175" I have two sets so if it's something you might be interested in let me know. The price is very cheap and they will work with a 3.750" stroke although there will be an extra .025" in the hole.

I also have a set of brand new Wiseco pistons that have -6cc in valve reliefs. They should make about 10.9:1 with a stock crank displacing 304 cubic inches. The Mahle should be at 11.4 with a 3.750 stroke and 323 cubic inches. I'm getting the forced induction itch right now and might be selling some of the motor building parts in my collection to fund it.

 

[conexion914]

I give in. I've been reading and searching cams any chance I get. Not to thread jack, but the 127500 seem to be the best choice for an NA motor from what I've been able to find.

I drag race, particularly bracket race and spend all of my time in the upper rpms when not daily driving.

The big debate I'm having is the lockouts vs limiters. On an otherwise stock motor which route should one go. Limiters allow the vct to work which allows for more power from what I understand. Any clarification would be sweet.

And sorry for the thread hijack but I think its relative as I've contemplated hot rods and the 127500s only.

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[jmauld]

Wouldn't the 127600 cams be better for drag racing? They require ported heads though.

 

[BruceH]

I give in. I've been reading and searching cams any chance I get. Not to thread jack, but the 127500 seem to be the best choice for an NA motor from what I've been able to find.

I drag race, particularly bracket race and spend all of my time in the upper rpms when not daily driving.

The big debate I'm having is the lockouts vs limiters. On an otherwise stock motor which route should one go. Limiters allow the vct to work which allows for more power from what I understand. Any clarification would be sweet.

And sorry for the thread hijack but I think its relative as I've contemplated hot rods and the 127500s only.

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It's not going to matter much, in fact for bracket racing I'd say lockouts will be more repeatable. They aren't going to affect driveability at all. Since you spend a significant amount of time in the higher rpms I'd lock them out advanced 6-8*. The higher rpm retard allows for more airflow in the higher rpms where the motor is consuming it.

Limiters would allow for 0 degrees of retard in the lower rpms, probably up to 3k would be about right, some datalogs would give more precise info. That would give you more power in the lower rpms but also less mpg.

IMO locking out the cams does less harm to performance when the cam has longer durations like the 127500. Shorter durations like the 127400 or 300 benefit more from vct imo. My opinion is based on my amateur datalogs and tuning skills. YMMV.

 

[07graygt]

Yea the plan is to make the boss block I got into a big bore stroker with some stage 3 rgr heads. I made with those cams and no long tubes or throttle body 334 rwhp. The setup you have is similar to where I am going but with a different head. The compression will be similar but I want to spray with it.The numbers and mods you have are awesome. Thanks for the explanations I appreciate it.

I was thinking about going with the 127550 if your going to spray. They are a blower cam but should be good with nitrous too.

 

[Raeko]

Spr 127500 over Mt. Much more labor intensive but well worth the better grind and extra rpm

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[conexion914]

It's not going to matter much, in fact for bracket racing I'd say lockouts will be more repeatable. They aren't going to affect driveability at all. Since you spend a significant amount of time in the higher rpms I'd lock them out advanced 6-8*. The higher rpm retard allows for more airflow in the higher rpms where the motor is consuming it.

Limiters would allow for 0 degrees of retard in the lower rpms, probably up to 3k would be about right, some datalogs would give more precise info. That would give you more power in the lower rpms but also less mpg.

IMO locking out the cams does less harm to performance when the cam has longer durations like the 127500. Shorter durations like the 127400 or 300 benefit more from vct imo. My opinion is based on my amateur datalogs and tuning skills. YMMV.

Thanks for your response. I see what you mean as there will be now way for vct to give me differing amounts of timing from run to run. Thanks again!

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[JONJON]

Anything I read helps so no problem with thread borrowing.LOL. Bruce I will be in contact about those pistons and stuff. 07Graygt I know they probably are but I have these cams for now and if after I build and spray they do not do the job to my liking trust me I will be changing them. Do you think that cam will do that much of a difference though? Thanks

 

[07graygt]

I didnt know you already had the cams. I dont think it would be to big a difference. From what ive read the biggest difference is the lsa. The blower cams stay open longer on the intake so you can draw more mixture in.

 

[retfr8flyr]

INHO if you are going to spend the money to do cams then it's kind of dumb not to spend the extra and get something that will really give you a performance boost. Get something with an aggressive enough profile that will require better springs and either lockouts or limiters. Hot Rod, Mutha Thumpers and such cams are mostly for the sound affect, they really don't give you much in performance gains, for the cost involved. The 127400, 127500 are good choices for a street driven N/A setup.


Earl

 

[JONJON]

INHO if you are going to spend the money to do cams then it's kind of dumb not to spend the extra and get something that will really give you a performance boost. Get something with an aggressive enough profile that will require better springs and either lockouts or limiters. Hot Rod, Mutha Thumpers and such cams are mostly for the sound affect, they really don't give you much in performance gains, for the cost involved. The 127400, 127500 are good choices for a street driven N/A setup.


Earl

The mutha thumprs need limiters and they gave me some good hp. I am at 334rwhp with no headers or throttle body. I dont mind spending the xtra money hell its only $700 or so but if its a minimal difference and I save that money why not, you know. Hell I had the worst trouble getting the right tune for the car. The first shop could not get my tune after spending $450 in dyno tune time. I then had to spend another $400 and got an X4 with the right tune from another shop and with that tune i made 334. The thumpr cams do not need limiters and give you almost nothing in power but these mutha thumprs made a big difference in power for me and I know when I get the 4.10 gears I will see some better times also. They have a huge duration with a .450 lift.

 

[JONJON]

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1434&sb=2
these are the cams I have

 

[2005Redfire6]

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1434&sb=2
these are the cams I have

Funny, comp says the 127500 is the biggest cam for the stock head too.... But it requires springs + lockouts/limiters... I have 127500s in a stroker motor I am picking up this weekend with lockouts.

 

[JONJON]

The cam card on mine also says it requires springs 26125. I think someone needs to redue the website because the two cams say the biggest cams on a stock head. One says on the website it needs springs the other one says it on the card and it will not run without the limiters. Oh well I love the way my car runs and sounds.