Ford Mustang Forum banner

Mutha Thumprs installed/Not so happy

3111 Views 24 Replies 11 Participants Last post by  sqidd
I just got back from the speed shop where I had the Mutha Thumprs and delete plates installed and Steeda UDPs. I only gained 22 HP. But my biggest concern is the personality change in the car. I and all the shop LOVE the sound and idle, but it is almost impossible to make a smooth/slow start and at 45 MPH in 5th, unless I am accelerating slightly or decelerating the car bucks or "jack-rabbits continuously. Even at freeway speeds of 60-65, I can feel the bucking, it's not as noticeable, but it can be felt. My wife (and I) loved the ride before and I think that it's going to be an uphill pull to get her to like the new feel. Have any of you guys experienced the same thing? (I have lockouts installed vs phase limiters per Doug at Bamachips).

I am just wondering if there is any wisdom out there on this?

flyboyjack:headscratch:
Status
Not open for further replies.
1 - 20 of 25 Posts
Sorry to hear that. I wonder if locking out the VCT contributes to the problem
Those cams are designed for higher rpm operation. That's what makes them tougher at low rpm to drive. That is why Ford went with VCT to make it drivable and have some good power. With locking the cams your stuck with what the cam designer, designed into the cam.
stlwgn: Not sure, I just know that Doug said he found that the cams w/ phase adapters made the engine run lean and detonate at higher power/RPM's so he is only recommending the lockouts.

flyboyjack
so if we open it back up and install the limiters it may/will smooth out a little?

Jack
stlwgn: Not sure, I just know that Doug said he found that the cams w/ phase adapters made the engine run lean and detonate at higher power/RPM's so he is only recommending the lockouts.

flyboyjack
How about upping the idle speed by 50 or so and reflash the tune? Might be worth a try.
You can't pussyfoot around with these cams. They were not made for low end rpm usage. Should of done your homework :nono:
I only gained 22 HP. But my biggest concern is the personality change in the car. I and all the shop LOVE the sound and idle, but it is almost impossible to make a smooth/slow start and at 45 MPH in 5th, unless I am accelerating slightly or decelerating the car bucks or "jack-rabbits continuously. Even at freeway speeds of 60-65, I can feel the bucking, it's not as noticeable, but it can be felt.

I just installed and tuned one of these cars recently with the mutha thumpr's and lock outs (not limiters) and while I didn't have any of the bucking you refer to (it was an auto) I am personally mixed with the "overall" personalty of the car. I gained 32 hp but the torque curve IMHO was all over the place, not a nice gentle curve, but with a few dips etc that I couldn't just tune out.

Overall it drove ok just not entirely impressed.
I'm not sure about these cams but my old time experance with High Performance cams is they won't smooth out utill you start getting into there designed rpm range. You could always up the rpms but that just makes it harder to pull out smoothly with a stick. With my old pushrod motors I spent a lot of time with the carbs to get them to run smooth at idle. If you know what to do with a Holley you can do it.

So I would try uping it 50 like Stl said and ever another 50 and try it, it can't heart. and you can alway go back with it. I would also talk to Doug and see what he says.
Thanks for the inputs. I'll try all of the above and I already am forming an email, (a nice one) to Doug. Just for the record, I DID do my homework and did extensive research into the cams. I explained EXACTLY what I wanted from a cam application to DOUG and this was HIS recommendation!! So I trusted his response. We'll keep plugging away at this!

flyboyjack
I love that bucking. Reminds me of a thoroughbred trying to get out of the stable. It's great and even better at high RPM's!:gringreen
I'm not sure about these cams but my old time experance with High Performance cams is they won't smooth out utill you start getting into there designed rpm range. You could always up the rpms but that just makes it harder to pull out smoothly with a stick. With my old pushrod motors I spent a lot of time with the carbs to get them to run smooth at idle. If you know what to do with a Holley you can do it.

So I would try uping it 50 like Stl said and ever another 50 and try it, it can't heart. and you can alway go back with it. I would also talk to Doug and see what he says.
Yep, exactly. My old Bronco had a high lift lunati cam in it and you could not just let out on the clutch and let it roll without giving it some gas. If you did, you would think it's one of those bounce cars with hydraulics lol.
I love that bucking. Reminds me of a thoroughbred trying to get out of the stable. It's great and even better at high RPM's!:gringreen
But thats not good for the drive train.
I have the same cam,however i have the adapters not the lockout.The tune is from Doug and the car is awesome,my is an auto.Call Doug,he'll fix you up in no time.
but it is almost impossible to make a smooth/slow start and at 45 MPH in 5th
Why on earth would you be accelerating from 45mph in 5th??????

We are talking about a Mustang here right?:scratchchin
Why on earth would you be accelerating from 45mph in 5th??????

We are talking about a Mustang here right?:scratchchin

Thats a big nono :badidea::badidea::badidea::badidea::badidea:

I just got out of first at that point :D:lol:
OK guys,

ENUFF!!! I don't accelerate from 45 MPH, I just try and maintain 45 MPH and it used to do it just fine w/o complaining (before cam install). It didn't lug the motor or anything. If I need speed I know how to use the clutch! BTW, I just took the wife out for a test spin, I thought it much better for me the second time out. 65 to 100+ in 3rd in no time flat!!! I do like that!! But now for part TWO: I have picked up an almost supercharger whine and the exhaust is DEFINITELY louder at cruise and idle. Did we "burn out the mufflers during the dyno pulls? More air thru the system? What?

flyboyjack
But now for part TWO: I have picked up an almost supercharger whine and the exhaust is DEFINITELY louder at cruise and idle. Did we "burn out the mufflers during the dyno pulls? More air thru the system? What?
You changed the cam timing and duration dramatically and the exhaust sounds different…….strange.

Running your car o a dyno is no different than driving down the road.
hey there flyboy, a couple of things

there are definitely tradeoffs, when you
go to thumpers or hot rods. i think some
of us want it all, the heavy lope and
perfectly smooth, stocklike driveability.

i have the hot rods and the car is more
cold blooded now, but it's a tradeoff i'm
willing to make.

some of your 5th gear driveability will
get corrected in your tune (i believe), so
hang in there and give the cams time
to grow on you.
See less See more
hey there flyboy, a couple of things

there are definitely tradeoffs, when you
go to thumpers or hot rods. i think some
of us want it all, the heavy lope and
perfectly smooth, stocklike driveability.

i have the hot rods and the car is more
cold blooded now, but it's a tradeoff i'm
willing to make.

some of your 5th gear driveability will
get corrected in your tune (i believe), so
hang in there and give the cams time
to grow on you.
It's definitely a learning experance. Like some say the cams are the heart of the engine. So if you change that it will effect it alot.
1 - 20 of 25 Posts
Status
Not open for further replies.
Top