Question to those who have blown your engine with a turbo/centri blower

[dlaude]

I've been seeing a lot of blown motor threads lately, but they seem to mostly be of the positive displacement blower type. I know that the centris and turbos have blown engines, too. But, is it roughly at the same power level? I know there's no "safe limit" and a lot has to do with the tune/detonation, but it seems that around 600 is "okay", but 650 and beyond is what I've seen referred to as "borrowed time". So, the turbo guys that blew it up, did you surpass that just because it was so easy to crank up the boost past those numbers? Or were you being safe and it blew up sooner than you expected?

I don't know TOO much about the differences (I am coming from the Terminator world where it was almost all PD blowers), but I would think that a centrifugal blower or turbo is a little more gentle (for lack of a better word haha) than the instant torque blast that your engine sees when you floor it at, say, 3500 RPM.

I don't know - long winded, sorry, but I guess my question is that will an engine let go at the same power level regardless of type of forced induction (all other being equal)? I know it's not an exact apples to apples comparison, but I think my overall question can somewhat be answered. Hoping you experienced and more knowledgeable (than me) will chime in with some insight. Thanks!

 

[4VFTW]

there are just way to many potential variables to say X-FI is more prone to hurt the motor.

 

[nonliberal]

I can't say what is more likely to blow the engine, but I would say the centri is least likely to be destroyed when the engine does let loose.

The PD is sitting right on top of the carnage, and the turbo ingests everything that comes out the exhaust. My last turbo car that snapped a valve chewed it up in the engine, transferred it through the head and spit it right through the turbo.

The whole damn thing was trashed.

 

[burke985]

Not all but most of the blown engines were because guys were pushing more than the coyote is known to handle safely and they knew they were on borrowed time.

 

[dlaude]

I can't say what is more likely to blow the engine, but I would say the centri is least likely to be destroyed when the engine does let loose.

The PD is sitting right on top of the carnage, and the turbo ingests everything that comes out the exhaust. My last turbo car that snapped a valve chewed it up in the engine, transferred it through the head and spit it right through the turbo.

The whole damn thing was trashed.

Oh yeah, another good point. I've heard of filter kits being used to collect any potential carnage going to the turbo, too, so that'd be an option to protect the turbo.

Not all but most of the blown engines were because guys were pushing more than the coyote is known to handle safely and they knew they were on borrowed time.

Know of any off-hand that weren't due to pushing the engine too far?


So, I guess to the turbo and centri blower guys, at what level did your engine blow?

 

[truebluedevil02]

A few things kill motors, Power(obviously), RPM, and detonation.

Power is misleading though as it some what depends on the delivery of the power. That is why you see more blown PD cars than Centri/turbo cars. the power and torque is nearly instant and is a big shock to the stock internals where as the turbo/centris build power more slowly so the internals are not as stressed right off the hit. So yes the "safe" power limit can change (A LITTLE) depending on the type of power adder you have. So lets say your tune is spot on, and you don't have any detonation. In that case IMO a personal "Safe"(safe meaning drive it for 20K+ miles and not worry about it) limit with a PD blower is around 580-600whp. Due to the less stressful nature of the turbos and centri blowers I would raise that to 650whp.

That being said, there have been cases where there were failures far lower than 600whp and there have been motors last for a long time well over the 700whp mark. Like someone stated earlier, there are just to many variables to say an exact # for sure. If you take a stock motor, toss a Paxton on it and beat it like it owes you money and spin it to the moon then 650whp might be pushing it. On the other hand if you limit the RPM's to 7000(stock), and only run it hard every now and again, then 650 would probably last a LONG time. But every motor, tune, car, driver, and location is different, and each one of those can change how much a motor will and will not hold.

 

[svt04cobra1]

I would not concentrate so much on what power adder blew up a motor but rather at what level. I think you already answered your question in your first post. ANYTHING above 650hp on a stock motor and your on borrowed time. If you get so much as bad gas it could be the end of your motor. Any power adder can make more then that so its not which one but at what level and you already have a good idea. Keep it at 600hp or less and you'll have a healthy motor for a long time as long as you have a good tune!!

 

[StevenStarke]

People blow #8 on NA coyotes, and other guys like Stretch are making 900whp on stock bottom ends. No rhyme or reason I guess

 

[mechanicboy]

I have a theory. Feel free to dissect it.

These PD blowers have bypass valves. When you slam the throttle the boost is made instantly because the bypass valve slaps close as soon as the vacuum is lost from the throttle opening. This causes an instant lean condition that the engine has trouble compensating for. The #8 cylinder is the farthest from the TB so it is most affected. It also has the hottest air intake temps (probably overall cylinder temps) because of this making it most susceptible for detonation. Lack of coolant circulation might play a roll.

Longtube headers and MAF sensors that are further from blower increase this affect.

Perhaps PD blowers need a stronger tip in enrichment? I come to this conclusion because the only time my truck had detonations in recent logs were only on tip in.

 

[five.slow]

its like playing bingo. i made over 700 on E85 with my old car and drove it every day with not one issue. had a few WOT passes with less that steller 91 pump gas too no issue. some have blown up with less power. im a firm believer in its how you treat the car. also rub on the car and call it baby here and there it cant hurt lol.

 

[five.slow]

I have a theory. Feel free to dissect it.

These PD blowers have bypass valves. When you slam the throttle the boost is made instantly because the bypass valve slaps close as soon as the vacuum is lost from the throttle opening. This causes an instant lean condition that the engine has trouble compensating for. The #8 cylinder is the farthest from the TB so it is most affected. It also has the hottest air intake temps (probably overall cylinder temps) because of this making it most susceptible for detonation. Lack of coolant circulation might play a roll.

Longtube headers and MAF sensors that are further from blower increase this affect.

Perhaps PD blowers need a stronger tip in enrichment? I come to this conclusion because the only time my truck had detonations in recent logs were only on tip in.

you have a wideband you can watch during tip in? my lightning never had a lean issue in tip in while tuned.

 

[burke985]

its like playing bingo. i made over 700 on E85 with my old car and drove it every day with not one issue. had a few WOT passes with less that steller 91 pump gas too no issue. some have blown up with less power. im a firm believer in its how you treat the car. also rub on the car and call it baby here and there it cant hurt lol.

Lol

 

[blackbeast12]

I love my paxton, its perfect for the street, I don't beat the crap outta my car. after having it for 7 months now it still surprises me when I go wot. That being said its all about how you treat your car! The reason why I didn't go with a pd is because I didn't want everything all at once. Especially on the street because traction on the street even with dr's is at a minimum! I'm not into spin fests.. I want to hook early and build boost through the rpms. My engine loves boost and shows no sign of stress with 8lb. in fact i think I'm gonna go with a 3.6 pulley and take it to 10lbs this spring! I have no worries about whether it can handle it!

 

[dlaude]

I would not concentrate so much on what power adder blew up a motor but rather at what level. I think you already answered your question in your first post. ANYTHING above 650hp on a stock motor and your on borrowed time. If you get so much as bad gas it could be the end of your motor. Any power adder can make more then that so its not which one but at what level and you already have a good idea. Keep it at 600hp or less and you'll have a healthy motor for a long time as long as you have a good tune!!

Yeah, that's what I'm thinking.

People blow #8 on NA coyotes, and other guys like Stretch are making 900whp on stock bottom ends. No rhyme or reason I guess

Good point. Some people say the day of the week it was built could contribute. I hope mine wasn't built on a Monday or Friday lol.

I have a theory. Feel free to dissect it.

These PD blowers have bypass valves. When you slam the throttle the boost is made instantly because the bypass valve slaps close as soon as the vacuum is lost from the throttle opening. This causes an instant lean condition that the engine has trouble compensating for. The #8 cylinder is the farthest from the TB so it is most affected. It also has the hottest air intake temps (probably overall cylinder temps) because of this making it most susceptible for detonation. Lack of coolant circulation might play a roll.

Longtube headers and MAF sensors that are further from blower increase this affect.

Perhaps PD blowers need a stronger tip in enrichment? I come to this conclusion because the only time my truck had detonations in recent logs were only on tip in.

Very interesting theory! I don't know enough to either agree or disagree on it though haha.

also rub on the car and call it baby here and there it cant hurt lol.

LMAO thanks, good tip!

I love my paxton, its perfect for the street, I don't beat the crap outta my car. after having it for 7 months now it still surprises me when I go wot. That being said its all about how you treat your car! The reason why I didn't go with a pd is because I didn't want everything all at once. Especially on the street because traction on the street even with dr's is at a minimum! I'm not into spin fests.. I want to hook early and build boost through the rpms. My engine loves boost and shows no sign of stress with 8lb. in fact i think I'm gonna go with a 3.6 pulley and take it to 10lbs this spring! I have no worries about whether it can handle it!

Nice! How many miles have you driven over those 7 months? Any track time? Do you do WOT pulls often? I see you're at 629hp, what DRs are you using?


Good info here, thanks! Keep the advice, tips, and comments coming!

 

[Rct851]

I'm not an expert but a serious lurker and what I've learned is this.

If you can spend $1000+ on your suspension
$6000 into your FI setup
$$exhaust
$$$wheels/tires
$air freshener

Then push the stock internals and skimp on a fuel system.. Then your a dumb dumb and deserve your new paper weight

All the talk about finding the safe "limit" sounds like people are stretching there wallets farther than they can afford.

I could afford a FI kit, but the extra 4-5k for a built motor and fuel system is to much for me, so by my own logic I CANT AFFORD IT

 

[burke985]

I'm not an expert but a serious lurker and what I've learned is this.

If you can spend $1000+ on your suspension
$6000 into your FI setup
$$exhaust
$$$wheels/tires
$air freshener

Then push the stock internals and skimp on a fuel system.. Then your a dumb dumb and deserve your new paper weight

All the talk about finding the safe "limit" sounds like people are stretching there wallets farther than they can afford.

I could afford a FI kit, but the extra 4-5k for a built motor and fuel system is to much for me, so by my own logic I CANT AFFORD IT

Alot of what you say is right but i disagree with some parts,as stated tons of times if you keep a safe tune and keep it around 600 whp and treat it right then the car will live a long time no matter what type of blower you put on the car and i dont think one is safer than the other that is a load of crap i dont care what anyone says. I'm going on 8 months with a TVS at 9-9.5 psi and car runs great , don't burn oil and is a blast to drive. Hell I'm still on the stock clutch at 617whp and the tranny is quiet as can be. Bottom line if you push any car to its limits and then beat it like a rag doll just like anything else it will break. If that is what you wanna do then your plan should be executed

 

[Rct851]

I just don't think we have enough 600hp cars with enough mileage with the blower (20k+) to definetively say what is reliable no matter the 1000 variables

 

[bam2012@TBR]

Alot of what you say is right but i disagree with some parts,as stated tons of times if you keep a safe tune and keep it around 600 whp and treat it right then the car will live a long time no matter what type of blower you put on the car and i dont think one is safer than the other that is a load of crap i dont care what anyone says. I'm going on 8 months with a TVS at 9-9.5 psi and car runs great , don't burn oil and is a blast to drive. Hell I'm still on the stock clutch at 617whp and the tranny is quiet as can be. Bottom line if you push any car to its limits and then beat it like a rag doll just like anything else it will break. If that is what you wanna do then your plan should be executed

+1 stock motor, trans, clutch. Return fuel with e85 but around 650/600whp. I have been over 600 for the last 16k and dd my 5.0. Great tune, Let it warm up keep eye on fluid / gauges and don't redline every time you drive it and it will last.

Total miles 35k and going strong.

 

[DEADLY FORCE]

I have a theory. Feel free to dissect it.

These PD blowers have bypass valves. When you slam the throttle the boost is made instantly because the bypass valve slaps close as soon as the vacuum is lost from the throttle opening. This causes an instant lean condition that the engine has trouble compensating for. The #8 cylinder is the farthest from the TB so it is most affected. It also has the hottest air intake temps (probably overall cylinder temps) because of this making it most susceptible for detonation. Lack of coolant circulation might play a roll.

Longtube headers and MAF sensors that are further from blower increase this affect.

Perhaps PD blowers need a stronger tip in enrichment? I come to this conclusion because the only time my truck had detonations in recent logs were only on tip in.

My number 8 cylinder looked just fine. My front cylinders on each head were the ones that failed. So for at least my engine, the number 8 theory didn't play a factor to its demise. Was pushing 609 to the wheels and 550 tq so it was just over the threshold of what people call safe, which is the 600 hp claim. Cylinder pressure was too much for the stock rods. I believe if you want to stay stock, the Paxton is a safer blower if you want boost it up. I like the idea of it not receiving blower damage either. I'm going to try to get my Roush professionally rebuilt by an authorized Eaton remanufacturer. We'll see how well it works. It can barely spin it by hand at the moment.

 

[NickSezz]

I have a theory. Feel free to dissect it.

These PD blowers have bypass valves. When you slam the throttle the boost is made instantly because the bypass valve slaps close as soon as the vacuum is lost from the throttle opening. This causes an instant lean condition that the engine has trouble compensating for. The #8 cylinder is the farthest from the TB so it is most affected. It also has the hottest air intake temps (probably overall cylinder temps) because of this making it most susceptible for detonation. Lack of coolant circulation might play a roll.

Longtube headers and MAF sensors that are further from blower increase this affect.

Perhaps PD blowers need a stronger tip in enrichment? I come to this conclusion because the only time my truck had detonations in recent logs were only on tip in.

This would be incorrect to assume.

The centri blowers also have a "bypass" that prevents boost from entering the manifold at idle and part throttle. The copperhead PCM calibrated correctly will react instantly to the change of air flow and apply the correct maps. Under pressure, #8 is no further from the path of flow than any other cylinder but it still will run the hottest due to the coolant path that is the same in either type of kit.

That said, you guys need to stop focusing on peak numbers to compare the effects of a PD and centri blower on an engine.

I will bring this graph up again as an example:

The PD blowers will make MORE power MOST of the time compared to the centri kits.

A centri car might make 650whp and 600wtq where peak TQ is made in the upper RPMs. Most street cars will spend more time in the mid-range RPMs than near redline where the TQ is considerably less than what a PD will make as seen on the graph at 4,000 RPMs.

Now if a PD car makes 600whp it is probably making around 500wtq where peak TQ is in the mid range. You will spend more time in the mid range when driving on the street and are most likely to stop the gas when going from a roll somewhere near 4,000-5,000 RPMs near peak TQ. This is how and where you will see a majority of failures when pushing the limits.